PURPOSE: To obtain an oil-hydraulic motor with selectivity only between high and low speed, wherein the construction is made simple, small, and light, by varying the inclination angle of the swash plate of hydraulic motor by a pushing member.

CONSTITUTION: A swash plate 4 is equipped with No.1 seat face 40 mating with the elongation side of a plunger 31 and the slide surface 42 contacted by a shoe 32. This swash plate 4 tilts round a fulcrum which consists of the intersection line of this No.1 seat face 40 with No.2 seat face 41. A pushing member P is furnished mating with the No.1 seat face 40, and the inclination angle of the swash plate 4 is varied by pressure of this pushing member P.