The flat grinding machine includes a plurality of carrier (9) which are located around and driven by a center gear (4) connected to a drive source. A work (15) retained by each carrier is intended to be ground by upper and lower fixed plate (2,3). A plurality of support gear mechanism (10) located around the center gear (4), each of which is constituted by a plurality of small gears (11-14) with a perpheral equi-distance. The carriers (9) are supported rotatably by the support gear mechanisms (10) in a position.
