To provide a hydraulic apparatus capable of ensuring high volumetric efficiency, and maintaining the high volumetric efficiency for a long period of time.

A hydraulic apparatus includes a pair of gears 20 with their tooth parts engaged with each other, a housing having a hydraulic chamber in which the pair of gears 20 is housed in an engaged state, and a bush to be housed in the hydraulic chamber of the housing while being abutted on both end faces of each gear. Chamfering M for setting the chamfering width of an intermediate section between a tooth tip and a tooth bottom to be larger than that of the tooth tip and the tooth bottom, is executed on an edge at the end face of each gear.