An indexing device comprising a base table (10), a turret (11) which indexes about a given rotary center relative to the base table (10), a pair of positioning engaging members (27) provided between the base table (10) and the turret (11), wherein at least one of the positioning engaging members (27) has an inclined tooth profile, and the positioning engaging members (27) are engageable with and disengageable from each other relative to the tooth profiles when they move in axial directions thereof relative to each other. The meshing of the tooth profiles are maintained by applying a pressing force to at least one of the positioning engaging members (27). When the turret (11) receives a load, a positioning displacement which occurs between the pair of positioning engaging members (27) is detected, and the pressing force applied to the positioning engaging members (27) is adjusted based on the result of detection.