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.
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 (i.e. league cup finals), golden goal rules were eliminated. Clubs now had to play the full extra time.
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:
Goal differential
Goals scored
Head-to-head results
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.
Updated to match(es) played on December 3, 2005. Source: J. League Division 1 Rules for classification: 1) points; 2) goal difference; 3) number of goals scored. (C) Champions; (R) Relegated Notes:
Updated to games played on December 3, 2005 Source: J. League Division 1 Notes: † Team played previous season in J2. ‡ Relocated from Ichihara to Chiba.