To firstly provide a much smoothly polished surface by polishing a work with abrasive particles of higher hardness than that of the work to greatly shorten the machining time, and secondly polishing the work by abrasive particles of lower hardness than that of the work in the same process.

A work is firstly polished with first abrasive particles 19b of higher hardness than that of the work in polishing a surface of a ceramic, the work is secondly polished with the abrasive particles in which second abrasive particles 19a of lower hardness than that of the work are mixed in the first abrasive grains, the ratio of the second abrasive particles 19b is increased in the subsequent stages, and the work is finally polished with the second abrasive powders 19b.