To accurately grind and polish a prism by adhering the prism onto the reference surface of a holding fixture with high accuracy when the prism is to be ground and polished.

Each prism 9 is held in each prism holding fixture 1 in order to grind and polish each prism 9. This device is equipped with each pressing member 8 pressing surfaces 9a other than a reference surface on which each prism 9 is adhered, a fixing plate 5 which supports each pressing member 8, and concurrently, regulates the pressing direction and position toward each prism by means of the rod of each pressing member 8, a base 2 supporting the fixing plate 5 by way of pillars 6, and having a holding fixture 1 rested, and with positioning members 3 and 4 which are fixed to the upper surface of the base 2 for positioning the holding fixture 1 by letting the aforesaid members be applied to the two side surfaces of the holding fixture 1 when the holding fixture 1 is to be rested thereon.