2005 J.League Division 1
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.
General
Promotion and relegation
- At the end of the 2004 season, Kawasaki Frontale and Omiya Ardija were promoted to J1.
- At the end of the 2004 season, there were no relegation to J2.
- At the end of the 2004 season, Tokushima Vortis and Thespakusatsu Gunma were promoted to J2 from JFL.
Changes in competition formats
- The Division 1 was expanded to 18 clubs, and Division 2 stays at 12 clubs.
- The format of Division 1 was changed from the double-season format to a single season.
- In games that require extra time in case of a tie, golden goal rules were eliminated. Clubs now had to play the full extra time.
Changes in clubs
- JEF United relocates from Ichihara to the prefecture capital, Chiba, and becomes JEF United Ichihara Chiba.
Clubs
Following eighteen clubs played in J.League Division 1 during 2005 season. Of these clubs, Omiya Ardija and Kawasaki Frontale were newly promoted clubs.- Albirex Niigata
- Cerezo Osaka
- FC Tokyo
- Gamba Osaka
- JEF United Ichihara Chiba
- Júbilo Iwata
- Kashima Antlers
- Kashiwa Reysol
- Kawasaki Frontale
- Nagoya Grampus Eight
- Oita Trinita
- Omiya Ardija
- Sanfrecce Hiroshima
- Shimizu S-Pulse
- Tokyo Verdy 1969
- Urawa Red Diamonds
- Vissel Kobe
- Yokohama F. Marinos
Format
Eighteen clubs will play in double round-robin 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:- Goal differential
- Goals scored
- Head-to-head results
;Changes from previous year
- Number of clubs competing increased from 16 to 18
- The season format was changed from the double-season format to a single season.
- Number of games per club increased from 30 games to 34 games per season.
Table
Awards
Individual
| Award | Recipient | Club |
| Player of the Year |  Best Eleven
|