PURPOSE: To reduce the number of control shafts and obtain a grinding face with high accuracy by installing a dressing device on the top stage slide and moving said dressing device by moving a grinder body.

CONSTITUTION: A dressing device 12 installed on a Y-axis slide 5 has an X-axis slide 13 which is slidable on the Y-axis slide in the X direction and, by rotating a handle 14, a feed screw 15 rotates moving the slide 13 in the X-axis direction. A rotary table 16 which revolves centering around a vertical C axis is revolvably supported on the slide 13. Thus, by installing a dressing device on the top stage slide of a grinder, the X-axis and Y-axis slides become unnecessary in the dressing device itself, simplifying the construction and the control device while enabling correction with high accuracy due to the improvement in rigidity.