To provide a cutter capable of cutting a bone joining material while preventing cracks from being generated on a cut portion of the bone joining material and the cut surface from being a chevron-shaped projecting surface having a ridge line portion.

The cutter for cutting a slender bone joining material in a direction crossing the length direction thereof includes two members 1, 2 which are overlapped with each other and can move in the relatively reverse direction. In the cutter, at least a material holding portion 3A for holding the bone joining material is formed on the one member 1, and a material cutting portion for cutting the bone joining material or a material cutting portion 4B serving also as a material holding portion is formed on the other member 2. When the bone joining member is cut with a material cutter of the other member while being held in the material holding portion of the one member, the bone joining material is hardly deformed when cut to prevent cracks. Further, since the cutting of the bone joining material is completed when the material cutting portion finishes relative movement from the one end to the other end of the material holding portion, the cutting surface becomes flat to prevent a ridge line portion from being formed.