A hydraulic machine of a radial piston type, comprising: a plurality of pistons arranged along a radial direction of the hydraulic machine; a plurality of rollers provided rotatably for the plurality of pistons, respectively; and a cam having a cam surface contacting the plurality of rollers and configured to rotate with a rotation shaft around a rotation axis of the rotation shaft of the hydraulic machine for a relative movement among the plurality of rollers and the cam; characterized in that a polishing direction of the cam surface is a direction along the rotation axis, or includes a first direction which is oblique to the rotation axis and a second direction which intersects the first direction and is oblique to the rotation axis, wherein the cam surface has a surface roughness Ra of not less than 0.1 and not greater than 0.3, the surface roughness being arithmetical mean deviation specified in JIS B0601, wherein the cam includes a high pressure region of the cam surface and a low pressure region of the cam surface, the high pressure region contacting the roller corresponding to a hydraulic chamber surrounded by the piston and the cylinder and undergoing pressure increase in the hydraulic chamber in a reciprocation cycle of the piston reciprocating in the cylinder, the low pressure region contacting the roller corresponding to a hydraulic chamber surrounded by the piston and the cylinder and undergoing pressure decrease in the hydraulic chamber in the reciprocation cycle, and wherein the low pressure region has a surface roughness Ra which is greater than that of the high pressure region. a plurality of pistons arranged along a radial direction of the hydraulic machine; a plurality of rollers provided rotatably for the plurality of pistons, respectively; and a cam having a cam surface contacting the plurality of rollers and configured to rotate with a rotation shaft around a rotation axis of the rotation shaft of the hydraulic machine for a relative movement among the plurality of rollers and the cam; characterized in that a polishing direction of the cam surface is a direction along the rotation axis, or includes a first direction which is oblique to the rotation axis and a second direction which intersects the first direction and is oblique to the rotation axis, wherein the cam surface has a surface roughness Ra of not less than 0.1 and not greater than 0.3, the surface roughness being arithmetical mean deviation specified in JIS B0601, characterized in that a polishing direction of the cam surface is a direction along the rotation axis, or includes a first direction which is oblique to the rotation axis and a second direction which intersects the first direction and is oblique to the rotation axis, wherein the cam surface has a surface roughness Ra of not less than 0.1 and not greater than 0.3, the surface roughness being arithmetical mean deviation specified in JIS B0601, wherein the cam includes a high pressure region of the cam surface and a low pressure region of the cam surface, the high pressure region contacting the roller corresponding to a hydraulic chamber surrounded by the piston and the cylinder and undergoing pressure increase in the hydraulic chamber in a reciprocation cycle of the piston reciprocating in the cylinder, the low pressure region contacting the roller corresponding to a hydraulic chamber surrounded by the piston and the cylinder and undergoing pressure decrease in the hydraulic chamber in the reciprocation cycle, and wherein the low pressure region has a surface roughness Ra which is greater than that of the high pressure region.