To miniaturize a hydraulic motor by providing a spring for a brake pressing a brake piston against a flange at an outside of a swash plate and a rotation stopping pin of the brake piston on a same circumference.

A plurality of spring holes 21 in which springs 9 pressing annular brake pistons 7 against the flange 13 are inserted are provided on a circumference outside of a swash plate 4, and a pin hole 22 in which the rotation stopping pin 8 is inserted is provided on the same circumference as the spring holes 21 on the flange 13. Consequently, an outer shape of the hydraulic pump can be downsized.