A hydraulic machine comprising: a rotation shaft ; a cam configured to rotate with the rotation shaft ; a cylinder disposed radially inside or outside the rotation shaft ; a piston configured to be reciprocable in the cylinder along a radial direction of the rotation shaft in conjunction with rotational motion of the cam ; a connecting rod including a first end portion connected swingably to the piston and a second end portion disposed opposite to the first end portion ; a hydrostatic pad disposed on the second end portion of the connecting rod , the hydrostatic pad including a sliding surface facing an outer surface of the cam ; and a lubricant-fluid supply channel disposed on the hydrostatic pad , for supplying a lubricant fluid to the sliding surface of the hydrostatic pad , wherein the hydraulic machine is configured so that a pressure in a working chamber formed by the piston and the cylinder changes cyclically and alternately between a first pressure P 1 and a second pressure P 2 larger than the first pressure P 1 , in accordance with the reciprocating motion of the piston , and wherein the hydrostatic pad is configured to retain a liquid film of the lubricant fluid between the sliding surface and the outer surface of the cam , characterized in that the hydrostatic pad is configured to retain the liquid film of the lubricant fluid having a thickness of d or more between the sliding surface and the outer surface of the cam at least when the pressure in the working chamber is the second pressure P 2 , wherein d is determined to correspond to an amount of deformation of the hydrostatic pad at the time when the pressure in the working chamber is the second pressure P 2 . a rotation shaft ; a cam configured to rotate with the rotation shaft ; a cylinder disposed radially inside or outside the rotation shaft ; a piston configured to be reciprocable in the cylinder along a radial direction of the rotation shaft in conjunction with rotational motion of the cam ; a connecting rod including a first end portion connected swingably to the piston and a second end portion disposed opposite to the first end portion ; a hydrostatic pad disposed on the second end portion of the connecting rod , the hydrostatic pad including a sliding surface facing an outer surface of the cam ; and a lubricant-fluid supply channel disposed on the hydrostatic pad , for supplying a lubricant fluid to the sliding surface of the hydrostatic pad , wherein the hydraulic machine is configured so that a pressure in a working chamber formed by the piston and the cylinder changes cyclically and alternately between a first pressure P 1 and a second pressure P 2 larger than the first pressure P 1 , in accordance with the reciprocating motion of the piston , and wherein the hydrostatic pad is configured to retain a liquid film of the lubricant fluid between the sliding surface and the outer surface of the cam , characterized in that the hydrostatic pad is configured to retain the liquid film of the lubricant fluid having a thickness of d or more between the sliding surface and the outer surface of the cam at least when the pressure in the working chamber is the second pressure P 2 , wherein d is determined to correspond to an amount of deformation of the hydrostatic pad at the time when the pressure in the working chamber is the second pressure P 2 . <EOS>