A semi-spherical shoe 1 includes a semi-spherical surface 1A and an end face 1B. The semi-spherical surface 1A comprises a sliding contact region 1a which is disposed in sliding contact with a semi-spherical recess 2B formed in a piston 2, and non-sliding contact regions 1b, 1b′ which are not disposed in sliding contact with the semi-spherical recess 2B. The non-sliding contact regions 1b, 1b′ have a surface roughness greater than the surface roughness of the sliding contact region 1a. The non-sliding contact regions 1b, 1b′ function as a lead-in of a lubricant oil to the sliding contact region 1a. As a consequence, there is provided a semi-spherical shoe 1 having an excellent sliding response as compared with a conventional arrangement in which the semi-spherical surface 1A has a uniform surface roughness over the entire region thereof.