To prevent a spring from being twisted even if a piston rotates on its own axis.

An axial piston machine is so constructed that a piston 4 is fitted in a cylinder block 2 in such a manner as to freely reciprocate, a spring bearer 5 and a spring 6 are in order arranged from the bottom surface side of a recessed part in the recessed part formed on the piston 4, and the piston 4 is pressed toward a swash plate by the spring 6. In the axial piston machine, a projection 4a is integrally formed on the bottom of the piston 4, and the tip of the projection 4a is pressed to the substantially central region of the spring bearer 5. Accordingly, even if the piston 4 rotates on its own axis while revolving, the rotating force by the rotation of the piston is made hard to be transmitted to the spring bearer 5 by the projection 4a so that the spring 6 is not twisted to prevent breakage.