PURPOSE: To uniformly work, for example, concave and covex surfaces in a hole, by carrying out a polishing process such that pressing pistons are opposed together with the surface of a work to be polished being held therebetween, and fluidic abrasive grain is subjected to relative movement while the press-hold condition of the fluidic abrasive grain is maintained by pressing the latter with the use of pressing members.

CONSTITUTION: In a polishing device for polishing the internal surface 1a of a work 1 to be polished, a pressing cylinder 2 and a working cylinder 3 are opposed, respectively to the upper opening and lower opening of the work to be polished, so that the surface 1a to be polished is held between both cylinders 2, 3. Pressing pistons 4, 5 are secured with ball screws 6, 7, respectively, which are driven by drive motors 8, 9 that are in turn controlled by a control device 10. Fluidic abrasive grain 11 is charged in a space defined between resilient membranes 12, 13 within the work 1 to be polished, between the cylinders 2, 3. The fluidic abrasive grain 11 is composed of resilient material such as, for example, rubber or synthetic resin, and abrasive grain, which are mixed together. Nitrile rubber or the like is mainly used as the above- mentioned rubber. Polymerized resilient material is broken into fragments having diameters from about 0.01W10mm, to which abrasive grain is mixed, or abrasive grain powder is bound to the surface of resilient particles so that the fluidic abrasive grain 11 is obtained to be used.