PURPOSE: To obtain the stabilized polishing accuracy independently of season factor by optimally controlling the working condition such as working pressure, polishing time and media initial temperature, and to obtain the stabilized polishing accuracy by setting the pressure in response to the media condition (temperature).

CONSTITUTION: An abrasive grain flow type working device is formed of an upper cylinder 1, a lower cylinder 2 and a jig 3. The working such as burring, corner rounding and surface polishing us performed by utilizing the characteristic of semi-solid high molecular material provided with viscosity and elasticity, and applying the pressure to the media 4, which is obtained by kneading the high molecular material with the polishing material, for pressure-contact movement on the inner and the outer surfaces of a material 5 to be worked.