PURPOSE: To obtain good sliding characteristics without elevating remarkably the surface roughness of a sliding face by allowing particles with a lower hardness than those of the sliding faces and a specified particle diameter to be adsorbed to the sliding face.

CONSTITUTION: Particles 3 with a lower hardness than those of sliding faces 1a and 2a and a particle diameter of 1/2 to 1-fold as large as the surface roughness of the sliding faces are allowed to be adsorbed to the sliding faces. If the particle 3 has a diameter of 1/2 or smaller of the surface roughness, no good effect can be obtd. If the particle diameter is the same as the surface roughness or larger, the energy of adsorption to the sliding face becomes weak. Therefore, the particle diameter is adjusted to be 1/2 to 1-fold as large as the surface roughness. As the hardness of the particle 3 largely affects wear of the sliding face, is is pref. that the hardness of the particle be 1/3 or smaller of the hardness of the sliding face. If the particle 3 has good affinity with the material of the sliding face, the powder formed by wearing adheres to the particle to enlarge it, so that it is pref. that the particle be made of a material with a different crystalline structure from that of the material of the sliding face or a material that does not produce agglomeration with the material of the sliding face.