A brake system includes a pad having a frictional surface, and a disc having a frictional surface sliding on the frictional surface. The frictional surface includes hard particles supported elastically and a plurality of protrusions arranged along a direction in which the frictional surface slides on the frictional surface, and when the frictional surface slides on the frictional surface, particles abut respective protrusions continuously while being displaced in the direction perpendicular to the frictional surface. Thus, wear resistance can be improved Since only the vicinities of the peaks of the hard particles and the vicinities of the peaks of the protrusions abut, the hard particles do not follow irregularities of the frictional surface, and thereby the hard particles and the protrusions repeat point contact. Thus, since the distance between the hard particles and the protrusions is stabilized and the adhesion frictional force is stabilized, a stable frictional force can be obtained.