The 2005 Formula Nippon Championship was the thirty-third season of premier Japanese single-seater racing, and the tenth under the Formula Nippon moniker. It was contested over nine rounds at five venues. The newly renovated Fuji Speedway returned to the calendar, replacing Sepang International Circuit. Miné Circuit, which had been a staple venue of the series since 1977, closed for spectator events after 2005. Eight teams and 17 drivers competed in the series.

This would be the final season for Mugen as the sole engine supplier to Formula Nippon, with Toyota and Honda introducing new engines for the 2006 season.

Satoshi Motoyama of Team Impul won his fourth series championship, becoming the most successful driver of the "modern era" of Japanese top formula racing.^[1]

All teams used tyres supplied by Bridgestone, Lola B03/51 chassis, and Mugen MF308 engines.

Team	#	Driver	Rounds
DoCoMo Team Dandelion Racing	1	Richard Lyons	All
	2	Naoki Hattori	All
Kondo Racing Team	3	Sakon Yamamoto	All
	4	Jaroslav Janiš	1–3
		Ronnie Quintarelli	4–9
Team 5ZIGEN	5	Tsugio Matsuda	All
Forum Engineering Team LeMans	7	Tatsuya Kataoka	All
	8	Takeshi Tsuchiya	All
Team Cerumo Takagi Planning with Cerumo	11	Katsuyuki Hiranaka	All
	12	Toranosuke Takagi	All
mobilecast Team Impul	19	Benoît Tréluyer	All
	20	Yuji Ide	All
arting Racing Team with Impul	23	Satoshi Motoyama	All
Carrozzeria Team MOHN	27	Masanobu Kato	1
	28	Hideki Noda	All
PIAA Nakajima Racing	31	André Lotterer	All
	32	Takashi Kogure	All

Suzuka

Motegi

Mine

Fuji

SUGO

2005 venues

All races were held in Japan.

Round	Track	Date	Pole position	Fastest lap	Winner	Team
1	Twin Ring Motegi	3 April	Yuji Ide	Katsuyuki Hiranaka	Richard Lyons	DoCoMoTeam Dandelion Racing
2	Suzuka Circuit	17 April	Benoît Tréluyer	Takashi Kogure	Yuji Ide	mobilecast Team Impul
3	Sportsland SUGO	15 May	Takashi Kogure	Hideki Noda	Satoshi Motoyama	arting Team Impul
4	Fuji Speedway	5 June	Richard Lyons	Tsugio Matsuda	Benoît Tréluyer	mobilecast Team Impul
5	Suzuka Circuit	3 July	Satoshi Motoyama	Yuji Ide	Satoshi Motoyama	arting Team Impul
6	Mine Circuit	31 July	Benoît Tréluyer	Yuji Ide	Yuji Ide	mobilecast Team Impul
7	Fuji Speedway	28 August	Richard Lyons	Satoshi Motoyama	André Lotterer	Nakajima Racing
8	Twin Ring Motegi	23 October	Satoshi Motoyama	Sakon Yamamoto	Satoshi Motoyama	arting Team Impul
9	Suzuka Circuit	27 November	Tsugio Matsuda	Benoît Tréluyer	André Lotterer	PIAA Nakajima Racing

Calendar changes

• The race in Sepang International Circuit was dropped, while Fuji returned with two races.

Scoring system

Rank	Name	MOT	SUZ	SGO	FUJ	SUZ	MIN	FUJ	MOT	SUZ	Points
1	Satoshi Motoyama	4	4	1	2	1	3	13	1	2	52
2	Yuji Ide	2	1	5	7	8	1	3	4	3	39
3	Richard Lyons	1	5	2	4	3	Ret	4	13	5	30
4	André Lotterer	11	Ret	9	Ret	Ret	10	1	Ret	1	20
5	Takashi Kogure	Ret	3	3	8	2	Ret	11	9	6	15
6	Benoît Tréluyer	6	9	Ret	1	Ret	Ret	12	11	4	14
7	Tsugio Matsuda	10	2	Ret	3	6	4	9	10	8	14
8	Takeshi Tsuchiya	5	Ret	4	Ret	Ret	5	5	3	Ret	13
9	Ronnie Quintarelli				5	5	2	Ret	5	10	12
10	Sakon Yamamoto	14	Ret	Ret	Ret	4	8	Ret	2	11	9
11	Tatsuya Kataoka	7	8	8	Ret	Ret	7	2	6	7	7
12	Naoki Hattori	3	6	6	10	7	6	7	7	14	7
13	Katsuyuki Hiranaka	8	Ret	Ret	6	Ret	Ret	6	12	9	2
14	Jaroslav Janiš	12	7	7							0
15	Toranosuke Takagi	9	Ret	11	9	10	9	8	Ret	12	0
16	Hideki Noda	Ret	Ret	10	Ret	9	Ret	10	8	13	0
17	Masanobu Kato	13									0

• 2005 Japanese Championship Formula Nippon