An excavating tooth is mountable onto an adapter, and includes a tooth body, an insertion cavity and a pair of supporting portions. The tooth body has a base end face and extends in a first direction. The insertion cavity is formed in the base end face and is acceptable to the adapter. The supporting portions project from an innermost part of the insertion cavity. The insertion cavity has a depressed portion and a pair of extending recesses. The depressed portion is formed between the pair of supporting portions. The pair of extending recesses extend in the first direction, and the pair of extending recesses are formed on both sides of the pair of supporting portions. A ground engaging tool includes an excavating tool body an excavating tooth and an adapter having a fixed portion fixed to the ground engaging tool body and an insertion portion inserted in the insertion cavity.