To accurately perform an adjusting operation for making the work shaft and the wheel shaft of a polishing device coaxial for a short period of time without requiring a skillful technique.

In the polishing device M1, a jig B4 having a concave tapered surface 5 is mounted in a floating state via a jig A2 on an upper shaft 1 where a lens is mounted via a work holder, a jig C7 having a convex tapered surface 6 is fixed on a lower shaft 8 where a polishing plate is mounted, and the jig B4 is fixed on the jig A2 of the upper shaft 1 with a screw 9 after the concave tapered surface 5 of the jig B4 is firmly stuck on the convex tapered surface 6 of the jig C7 by fitting to the concave tapered surface 6 of the jig C7 while descending the upper shaft 1. Consequently, the adjustment of coaxiality between an axial direction 1Z of the upper shaft 1 and an axial direction 8Z of the lower shaft 8 can be simply and quickly carried out without requiring a specific skill.