Tool body

A tool body in which a cutting insert can be replaced easily is provided. The tool body which fixes the indexable cutting insert includes an insert mounting seat which is provided on a first surface of the tool body, a clamp member which binds the cutting insert placed on the insert mounting seat, and an operating member which operates the clamp member. The operating member can lower the clamp member from the first surface toward a second surface of the tool body on an opposite side thereof to the first surface and can raise the clamp member from the second surface toward the first surface. The clamp member has a hook portion which is brought into contact with a diameter reducing portion formed on an inner peripheral surface of a mounting hole of the cutting insert in a state where the clamp member is lowered.