A tool holder is provided with a main body, a taper cone, a working portion, a coolant flow passage, and an adjuster. The taper cone includes a taper portion and movable in an axial direction of the main body. The working portion is mounted on an outer peripheral portion of the main body and includes a taper bottom surface which engages with the taper portion. The taper bottom surface is movable in a radial direction of the main body based on a movement of the taper cone in the axial direction. A coolant flows through the coolant flow passage such that a part of the coolant presses and moves the taper cone in the axial direction and another part of the coolant flows out to an outside so as to adjust a pressing force. The adjuster is fitted into a hole penetrating the main body and includes a coolant flow-out hole for adjusting a flow-out of the coolant.