FORM 6-K

SECURITIES AND EXCHANGE COMMISSION

Report of Foreign Private Issuer

Pursuant to Rule 13a-16 or 15d-16
of the Securities Exchange Act of 1934

For the month of October, 2004

Commission File Number 1-7616

PIONEER CORPORATION

4-1, MEGURO 1-CHOME, MEGURO-KU, TOKYO 153-8654, JAPAN

Indicate by check mark whether the registrant files or will file annual reports under cover Form 20-F or Form 40-F:

Form 20-F  þ                    Form 40-F  o

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(1):                               

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7):                               

Indicate by check mark whether by furnishing the information contained in this Form, the registrant is also thereby furnishing the information to the Commission pursuant to Rule 12g3-2(b) under the Securities Exchange Act of 1934.

Yes  o                    No  þ

If “Yes” is marked, indicate below the file number assigned to the registrant in connection with Rule 12g3-2(b): 82-

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

This report on Form 6-K contains the following:

For Immediate Release
October 28, 2004

Pioneer Announces Second-Quarter and Semiannual Results for Fiscal 2005

TOKYO — Pioneer Corporation today announced its consolidated second-quarter and semiannual business results, and non-consolidated semiannual business results, for the period ended September 30, 2004.

Consolidated Financial Highlights

- 1 -

Consolidated Business Results
The second quarter of fiscal 2005, ended September 30, 2004, resulted in consolidated operating revenue of ¥181,560 million (US$1,635.7 million), an 8.4% increase from the corresponding period in the previous year. Operating income was ¥8,269 million (US$74.5 million), a 16.3% decrease, and net income was ¥3,312 million (US$29.8 million), a 65.3% decrease. The average value of the yen was up 6.9% against the U.S. dollar and down 1.6% against the euro from the corresponding period in the previous year.

Home Electronics sales increased 6.7% to ¥71,717 million (US$646.1 million) from the corresponding period last year. In Japan, sales rose 29.6% to ¥21,809 million (US$196.5 million) primarily due to a large increase in sales of home-use plasma displays and DVD recorders, despite the decreased sales of recordable DVD drives for personal computers (PCs). Overseas sales were substantially the same as in the corresponding period last year at ¥49,908 million (US$449.6 million), reflecting a decline in sales of recordable DVD drives and audio products worldwide, as well as contraction of our digital cable TV set-top box business in North America, which offset an increase in sales of home-use plasma displays and DVD recorders worldwide.

Car Electronics sales amounted to ¥74,770 million (US$673.6 million), up 11.4% over the corresponding period in the previous year. In Japan, sales increased 14.3% to ¥29,453 million (US$265.3 million), reflecting increased car navigation system sales to automobile manufacturers, despite decreased sales of such systems to the consumer market. Overseas sales increased 9.6% to ¥45,317 million (US$408.3 million), primarily due to higher sales of car navigation systems in North America and Europe, audio products to automobile manufacturers in North America and car audio products in Asia and Central and South America.

Royalty revenue from Patent Licensing decreased 22.5% from the corresponding period in the previous year to ¥3,864 million (US$34.8 million). This was due to a decline in royalty revenue resulting from the expiration of the Company’s optical disc-related patents in certain areas.

Others sales increased 10.6% from the corresponding period in the previous year to ¥31,209 million (US$281.2 million). In Japan, sales were lower by 4.4%, at ¥13,882 million (US$125.1 million) primarily due to a decrease in sales of organic light-emitting diode (OLED) display panels and a sales shift from Japan to China of semiconductors related to laser pickups, despite the increase in sales of factory-automation (FA) systems. Overseas, sales were up 26.5% over the previous year to ¥17,327 million (US$156.1 million), primarily due to increased sales of devices for cellular phones and semiconductors related to laser pickups in China, as well as FA systems in Asia, despite decreased sales in North America and Europe of business-use plasma displays.

- 2 -

Operating income decreased 16.3% from the corresponding period of the previous year to ¥8,269 million (US$74.5 million). This decrease occurred despite increased net sales, and reflected decreased gross profit margin due to intensified price competition for our major products and decreased profit from patent licensing as a result of a decline in royalty revenue. Net income came to ¥3,312 million (US$29.8 million), a 65.3% decrease, due to decrease in operating income as well as absence of the ¥4,729 million income from discontinued operations recorded in the corresponding period of last year as a result of the sale of subsidiaries in the audio/video software business.

Semiannual results — Consolidated operating revenue for the six-month period ended September 30, 2004, was ¥345,047 million (US$3,108.5 million), a 7.8% increase compared with the corresponding period last year. Net income for the period decreased by 61.5% to ¥4,809 million (US$43.3 million).

Cash Flows
Net cash provided by operating activities for the second quarter ended September 30, 2004 was ¥1,645 million (US$14.8 million), a decrease of ¥15,161 million from ¥16,806 million for the corresponding period of last year. In investing activities, ¥49,278 million was used mainly for the acquisition of a plasma display production subsidiary from NEC Corporation and purchase of fixed assets.

Dividend Policy and Interim Dividend
The Company’s policy on dividends allows for continued and stable dividend payment. The Company determines the appropriate dividend amount, taking into consideration its financial condition, business results, internal reserves and other factors, all on a consolidated basis.

In line with this policy, an interim dividend of ¥12.5 (US$0.11) per share of common stock, the same amount as in the corresponding period last year, will be paid to the shareholders of record as of September 30, 2004 (Japan time).

Addressing Current Challenges
The business environment remains severe, characterized by uncertain economic conditions in our major markets, Japan, North America and Europe, price competition beyond our projections in our major product categories, and exchange rate fluctuations. In order to achieve the medium-term management plan, the Company is concentrating resources on strategic businesses as described below to recover profits and improve efficiency.

In our plasma display business, we are working to build up capacity of the production system to meet fast-growing demand, thereby increasing profitability of the business. Our recently added fourth line has expanded our production capacity to approximately 600,000 units a year. Our new plant acquired from NEC Corporation in September 2004 further increased Pioneer’s plasma display production capacity,

- 3 -

bringing it to a total of approximately 1,100,000 units a year.

In the DVD business, markets for DVD recorders, especially those with large-capacity hard disk drives (HDDs), and recordable DVD drives for PCs, are rapidly growing. On the other hand, price competition is getting harsher. To cope with the situation, we are advancing cost cutting, for example, by carrying out integrated production from laser pickups to finished products in China. We are also expanding sales of drive units of DVD recorders to other manufacturers.

In our car electronics business, we continue our efforts to strengthen our leadership in the consumer and OEM (original equipment manufacturing) markets. Our car navigation systems enjoy an excellent reputation in Japan, and we intend to expand this business in Europe and North America. In the car audio business, we plan to fortify our strong position with distinctive new products, and maintain earnest sales efforts in such growing markets as China and Central and South America.

Our drive to minimize operating costs and expenses worldwide continues. We are expanding production in China to reduce overall manufacturing costs; implementing an expense supervision system to lower the ratio of our selling, general and administrative expenses to consolidated operating revenue; and applying supply chain management to review and optimize inventory control worldwide, for everything from parts procurement to retailer supply, on a weekly basis. We believe that such initiatives help us return to growth in profitability and improve cash flows.

Business Forecasts for Fiscal 2005
Assuming that the yen-U.S. dollar and the yen-euro exchange rates average ¥105 and ¥130, respectively, through the end of fiscal 2005, ending March 31, 2005, we have revised our consolidated business forecasts for fiscal 2005, from those announced in July 2004, as follows:

(In millions of yen)

The projection of operating revenue for fiscal 2005 stays unchanged. The acquisition of a plasma display production subsidiary from NEC Corporation in September 2004 is expected to increase operating revenue. However, reflecting intensified competition and falling prices in the markets, sales of DVD recorders and recordable DVD drives are not growing as previously projected, and in addition, the scheduled shipment to a new customer of OLED display panels is to be delayed until the next fiscal year.

- 4 -

The projections of operating income, income before income taxes and net income are revised downward, due to the decreased profit margins caused by the harsher competition and downward pressures on prices with the Company’s major lines of products, despite the efforts to lower costs in parts purchases and product manufacturing.

Corporate Policy
Customer satisfaction is our highest priority. In keeping with Pioneer group’s philosophy to “Move the Heart and Touch the Soul,” we strive to develop and provide advanced, high-quality, value-added electronics products that deliver satisfaction, comfort and convenience, and create new forms of entertainment.

Accordingly, in August 1998 we devised a medium-term management plan, and set the following four business targets and two financial targets to be achieved by March 2006.

Business targets:

Financial targets for fiscal year ending March 2006:

Cautionary Statement with Respect to Forward-Looking Statements
Statements made in this release with respect to our current plans, estimates, strategies and beliefs, and other statements that are not historical facts are forward-looking statements about our future performance. These statements are based on management’s assumptions and beliefs in light of the information currently available to it. We caution that a number of important risks and uncertainties could cause actual results to differ materially from those discussed in the forward-looking statements, and therefore you should not place undue reliance on them. You also should not believe that it is our obligation to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise. We disclaim any such obligation. Risks and uncertainties that might affect us include, but are not limited to, (i) general economic conditions in our markets, particularly levels of consumer spending; (ii) exchange rates, particularly between the yen and the U.S. dollar, euro, and other currencies in which we make significant sales or in which our assets and liabilities are denominated; (iii) our ability to continue to design and develop and win acceptance of our products and services, which are offered in highly competitive markets characterized by continual new product introductions, rapid developments in technology and subjective and changing consumer preferences; (iv) our ability to successfully implement our business strategies; (v) our ability to compete, and develop and implement successful sales and distribution strategies in light of technological developments in and affecting our businesses; (vi) our continued ability to devote sufficient resources to research and development, and capital expenditure; (vii) our ability to continuously enhance our brand image; (viii) the success of our joint ventures and alliances; and (ix) the outcome of contingencies.

- 5 -

Pioneer Corporation is one of the leading manufacturers of consumer- and business-use electronics products such as audio, video and car electronics on a global scale. Its shares are traded on the New York Stock Exchange (ticker symbol PIO), Euronext Amsterdam, Tokyo Stock Exchange, and Osaka Securities Exchange.

# # # # # #

The U.S. dollar amounts in this release represent translation of Japanese yen, for convenience only, at the rate of ¥111=US$1.00, the approximate rate prevailing on September 30, 2004.

Attachments:

For further information, please contact:
Investor Relations Department, Corporate Communications Division
Pioneer Corporation, Tokyo
Phone: +81-3-3495-6774 / Fax: +81-3-3495-4301
E-mail: pioneer_ir@post.pioneer.co.jp
Website: http://www.pioneer.co.jp/corp/ir/index-e.html

- 6 -

Pioneer Corporation and Subsidiaries

(In millions of yen)

(In millions of yen)

Pioneer Corporation and Subsidiaries

(In millions of yen)

(In millions of yen)

Pioneer Corporation and Subsidiaries

(In millions of yen)

Pioneer Corporation and Subsidiaries

(In millions of yen)

(In millions of yen)

Pioneer Corporation and Subsidiaries

The following segment information is prepared pursuant to the regulations under the Securities and Exchange Law of Japan.

<Business Segments>

(In millions of yen)

(In millions of yen)

<Geographic Segments>

(In millions of yen)

Pioneer Corporation and Subsidiaries

Notes:

Pioneer Corporation—Parent Company Only

(In millions of yen)

(In millions of yen)