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.
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<small>* The number in brackets denotes the number of times that the footballer has appeared in the Best 11.</small>