Abstract: A semi-spherical shoe 1 includes an end face 1B which is disposed in sliding contact with a swash plate 3 and a semi-spherical surface 1A which is disposed in sliding contact with a semi-spherical recess 2A formed in a piston 2. A spherical recess 1C is formed in the top portion of the semi-spherical surface 1A to define a space 4 which serves as a reservoir of lubricant oil between the spherical recess 1C and the semi-spherical recess 2B. If the volume of the space 4 which serves as a reservoir of lubricant oil is increased, an accumulation of abraded power in the spherical recess 1C which forms the space can be prevented in a favorable manner.