A hydraulic motor capable of minimizing a wear caused on a rotating brake disk of a brake device, wherein a rotating brake disk (32) which forms a plurality of arc-shaped grooves (17) apart from each other in circumferential direction and constitutes a brake device (31) is provided on the outer peripheral side of a cylinder block (15), and a plurality of arc-shaped projections (33) engaged with the arc-shaped grooves (17) and a plurality of radial contact parts (34) are provided on the inner peripheral side of the rotating brake disk (32) and the plurality of radial contact parts (34) are allowed to face the outer peripheral surface of the cylinder block (15) so that they can be brought into contact with each other, whereby, at the time of braking of the hydraulic motor (10), the movement of the rotating brake disk (32) in rotating direction is controlled by the arc-shaped projections (33) and the movement of the rotating brake disk (32) in radial direction is controlled by the radial contact parts (34).