To improve stable working accuracy by preventing cracks and breaks of a work 15 occurring in the process of polishing the square work 15 in a planetary gear type polishing device.

In this carrier, in order to polish a thinner work 15 while preventing cracks and breaks of the work 15 due to deformation of machining surfaces of an upper plate and a lower plate 11 occurring in the process of polishing, the shape of a work holding hole 16 of the carrier 14 is such that in the process of polishing, the work 15 draws a locus of a character 8-shaped to the upper plate 10 and the lower plate 11 by rotation and revolving motion of the carrier 14, whereby the shape of the work holding hole 16 is thus added to make the machined work 15 have higher accuracy and decrease cracks and breaks.