|Ceased||1956 (revived in 1961)|
|No. of teams||7|
The Eastern League (イースタン・リーグ) is one of the two minor leagues ("ni-gun") of Japanese professional baseball. The league is owned and managed by the Central League of Nippon Professional Baseball (NPB). Teams in the Eastern League generally play an 80-game schedule every year.
In 1954 the six teams of NPB's Central League agreed to form their own minor league — the Shin Nippon League (or "New Japan League") — as a complement to the already extant Kansai Farm League, which had begun play in 1952. The minor league affiliates of the Chunichi Dragons and Hanshin Tigers moved over from the Kansai Farm League.
The initial roster of Shin Nippon League teams (NPB parent team in parentheses):
Both minor leagues decided to join forces with Nippon Professional Baseball in 1955, and the 14 farm teams of the Central League and Pacific League were split up to create the Eastern League and the Western League, each with seven teams.
The Eastern League contained the minor league teams of the seven professional teams that had their homefields in the Eastern region of Japan (NPB parent team in parentheses):
The Eastern League restarted in 1961 with five teams: in the interim the Daiei Stars and the Takahashi Unions (formerly the Tombo Unions) had merged into the Daiei Unions, who in turn merged with the Mainichi Orions to ultimately form the Daimai Orions (now known as the Chiba Lotte Marines). From that point until the year 2000, all Japanese minor league teams used the same name as their NPB parent club.
In 2005 the Tohoku Rakuten Golden Eagles were formed to join NPB, and their farm team became part of the Eastern League as well.
The league currently contains the minor league affiliates of seven Japanese professional teams. With a few exceptions, Eastern League teams currently carry the same name, and use the same uniforms, as their parent team.
Current teams (minor league homefield shown in parentheses):