1930 in Japanese baseball
 Professional Baseball
 High School Baseball
The 16th National High School Baseball Championship featured a total of 541 schools competing for 22 spots in the finals at Koshien. In the championship game Hiroshima High School (Hiroshima) defeated Suwa Sanshi High School (Nagano) by a score of 8 - 2.
The 7th National High School Baseball Invitational Tournament featured 16 schools competing in the tournament at Koshien. In the championship game Number One Jinkou High School (Hyogo) defeated Matsuyama High School (Ehime) by a score of 6 - 1.
 University Baseball
 Tokyo Big6 Baseball League
 Tohto University Base Ball League
The Tohto University Base Ball League was founded and held only a single season.