Indonesia Super League U-21
|Number of teams||22|
|Level on pyramid||1|
|Current champions||Semen Padang U-21
|Most championships||Persela U-21 (2)|
Indonesia Super League U-21 is a junior level league involving U-21 team (reserve team) of participating clubs in the Indonesia Super League. Building and managing a complete U-21 team is one of the requirements for clubs participating in the ISL, as regulated by the Football Association of Indonesia (PSSI).
Different with the main ISL league, in this junior competition, the 18 participating clubs are divided into 3 groups considering geographical locations. Winners from each groups and the best runner up go through the knock-out phase (semifinal and final), which is held once each.