PURPOSE: To manufacture easily the rotary cutter for wood working that can cut groove with flat bottom, by forming the structure whereby the edge grinds parallely with the rotation axis in a dimension where the edge is parallel with the work head axis.

CONSTITUTION: On the upper end of the work head shaft 3 rotating on the fixed position the rotary cutter 1 whose edge 2a is not ground is fixed by the nut 4. With such an arrangement, while the cutter 1 is revolved a little intermittently, when it stops the rotary grinding body 5 mounted on the fixed position is revolved and moved up and down to grind the edge 2a of the cutter 2. The width of the grinding surface 5a of the grinding body 5 is wider than the moving width of the edge 2a of the cutter 1, and is parallel with the rotating axis of the shaft 3. By this formation the rotary cutter for wood working that can cut groove with flat bottom can easily be manufactured.