| Competition: | J.League Division 1 |
| Season: | 2005 |
| Winners: | Gamba Osaka 1st J.League title 1st Japanese title |
| Continentalcup1: | Champions League |
| Continentalcup1 Qualifiers: | Gamba Osaka Tokyo Verdy 1969 (all to the group stage) |
| Relegated: | Kashiwa Reysol Tokyo Verdy 1969 Vissel Kobe |
| League Topscorer: | Clemerson (33 goals) |
| Matches: | 306 |
| Total Goals: | 873 |
| Highest Attendance: | 55,476 (Round 9, Urawa Red Diamonds vs. Nagoya Grampus Eight) |
| Lowest Attendance: | 3,267 (Round 5, Tokyo Verdy 1969 vs. Sanfrecce Hiroshima) |
| Average Attendance: | 18,765 |
| Prevseason: | 2004 |
| Nextseason: | 2006 |
The 2005 J.League Division 1 season was the 13th season since the establishment of J.League Division 1. It began on March 5 and ended on December 3, followed by J. League promotion/relegation series matches on December 7 and 10.
Following eighteen clubs played in J.League Division 1 during 2005 season. Of these clubs, Omiya Ardija and Kawasaki Frontale were newly promoted clubs.
Eighteen clubs will play in double round-robin (home and away) format, a total of 34 games each. A club receives 3 points for a win, 1 point for a tie, and 0 points for a loss. The clubs are ranked by points, and tie breakers are, in the following order:
A draw would be conducted, if necessary. However, if two clubs are tied at the first place, both clubs will be declared as the champions. The bottom two clubs will be relegated to J2, while the 16th placed club plays a two-legged Promotion/relegation Series.
| Rank | Scorer | Club | Goals[1] |
|---|---|---|---|
| 1 |  Clemerson | Gamba Osaka | |
| 2 | Washington | Tokyo Verdy 1969 | |
| 3 | Edmílson | Albirex Niigata | 18 |
| Magno Alves | Oita Trinita | ||
 Hisato Satō | Sanfrecce Hiroshima | ||
| 6 | Juninho | Kawasaki Frontale | 16 |
| Masashi Oguro | Gamba Osaka | ||
| 8 | Alex Mineiro | Kashima Antlers | |
| 9 | Robert Cullen | Júbilo Iwata | |
| 10 | Ryoichi Maeda | Júbilo Iwata | 12 |
| Seiichiro Maki | JEF United Ichihara Chiba | ||
| Yuki Abe | JEF United Ichihara Chiba |
| Award | Recipient | Club |
|---|---|---|
| Player of the Year | Clemerson | Gamba Osaka |
| Young Player of the Year | Robert Cullen | Júbilo Iwata |
| Manager of the Year | Akira Nishino | Gamba Osaka |
| Top Scorer | Clemerson | Gamba Osaka |
| Fair Play Player Award | Masashi Oguro | Gamba Osaka |
| Teruyuki Moniwa | FC Tokyo | |
| Referee of the Year | Kazuhiko Matsumura | |
| Assistant Referee of the Year | Masatoshi Shibata | |
| Meritoriousness Player Award | Bismarck |
| Position | Footballer | Club | Nationality | |
|---|---|---|---|---|
| GK | Motohiro Yoshida (1) | Cerezo Osaka | ||
| DF | Ilian Stoyanov (1) | JEF United Ichihara Chiba | ||
| DF | Marcus Tulio Tanaka (2) | Urawa Red Diamonds | ||
| DF | Yuji Nakazawa (4) | Yokohama F. Marinos | ||
| MF | Fernandinho (1) | Gamba Osaka | ||
| MF | Mitsuo Ogasawara (5) | Kashima Antlers | ||
| MF | Tatsuya Furuhashi (1) | Cerezo Osaka | ||
| MF | Yasuhito Endō (3) | Gamba Osaka | ||
| MF | Yuki Abe (1) | JEF United Ichihara Chiba | ||
| FW | Clemerson (1) | Gamba Osaka | ||
| FW | Hisato Satō (1) | Sanfrecce Hiroshima |
Ibrahima Rene Camara
