Cemented carbides are used for numerous machine elements as one of the important tribomaterials, because of the superior wear resistance. But, shallow numerous cracks are occasionally induced on the rubbing surface. In this work, SiC and Si₃N₄ were rubbed against various kinds of cemented carbides to clarify factors inducing the cracks and to propose a possible mechanism for cracking. FEM analyses were also carried out to reveal a possible mechanism for cracking. The main results obtained are as follows: Cracks occur not on the ceramic surface but on the cemented carbide. The distance between adjacent cracks increases with the increase of Co/Ni binder content in cemented carbide. The cracks on cemented carbide are induced more easily with Si₃N₄ than with SiC.