To provide a tool to assist grinding of the ridge surface of the edge of a kitchen knife in a flat state accurately corresponding to a cutting edge angle, improves general purpose, and effect grinding by using a grinding tool on a market without being influenced by the degree of skill.

This tool is of structure that a body 1 operated by two hands and a kitchen knife holding part 2 to mount a kitchen knife are interconnected at a connection shaft 3 part. The kitchen knife is inserted in the handle holding frame 8 of the kitchen knife holding part 2 and a handle holding frame 9 and fixed by moving a handle central hold part 11 by rotating a wing bolt 14. In grinding, the handle 4 is placed on a grinding surface with the cutting edge of the kitchen knife pointing this side and with the tubular part of a mounting part 7a grasped by the other hand. Forefingers are applied on a finger putting part 6b and a finger putting part 7b, and arms are lightly moved longitudinally as a ridge surface is pressed thereagainst.