To uniformly grind a kitchen knife over the whole length of a blade by providing a blade part supporting surface to keep a constant angle between the blade part of the kitchen knife and the surface to be ground, and applying the magnetic force to the blade supporting surface.

A V-shaped groove 5 is provided integratedly with a housing above grinding wheels 1. When a kitchen knife is ground, a blade part of the kitchen knife is inserted in the groove 5, and the blade is placed on grinding faces 3, 3 of the grinding wheels 1 to grind. A square large window 6 is provided in an inner surface of the groove 5, and a side of a magnet 7 is exposed from the window 6. The blade part of the kitchen knife is attracted to the groove 5 by the magnetic force only by placing the blade part of the kitchen knife on the groove 5 while grinding the blade, and the blade can be easily ground at the constant angle.