To provide a cutter sharpening device having a simple structure, with which a grinding element can be uniformly applied to a side surface of a blade edge.

A cutter sharpening device includes a bearing 11 provided with a rotary shaft 8 rotatably, and a grinding element 5 provided at a center of the rotary shaft 8 and having a pair of conical surfaces 6, 7. Grinding surfaces 6A, 7B are formed on the pair of conical surfaces 6, 7, the bearing 11 supports the rotary shaft 8 to be movable vertically, the rotary shaft 8 is provided to be axially movable with respect to bearings 11, 11 on both sides, and synthetic resin-made urging means 81, 81 are provided between the grinding element 5 and the bearings 11, 11. Further, as a cutter guided in a front-back direction to intersect, the rotary shaft 8 with a lid body is sharpened while the grinding surfaces 6A, 7A are uniformly pressed to the side surface of the cutter by the urging means 81, uniform grinding can be performed, and a washer or the like becomes unnecessary.