PURPOSE: To provide an indexing device to be mounted on a machining center, etc., whereby an indexing shaft is located accurately in a plurality of positions at constant angular intervals while a low-cost fluid pressure cylinder is used.

CONSTITUTION: A ratchet 14 is fixed onto an indexing shaft 12 supported on a device body 11, and four indexing pawls 16 are furnished on the periphery of the ratchet at a constant pitch. A pinion 17 is coupled with the indexing shaft 12 through a one-way clutch 21 and meshed with a rack 25 coupled with a piston 24 of a pneumatic cylinder 23 for indexing, and thereby the indexing shaft 12 is rotated intermittently in one direction at 90-deg. intervals. This pneumatic cylinder 23 and another pneumatic cylinder 43 for location are put under tuning control using a common pneumatic circuit. When the indexing shaft 12 is stopped, the piston rod 44 of the cylinder 43 is engaged by the front surface of the indexing pawl 16 so that the ratchet 14 is energized in the reverse direction, and the back surface of the pawl 16 is pressed to a stopper pin 31 perpendicularly intersecting the piston rod 44 so that the reverse rotation of the ratchet 14 is restricted.