A tool holder includes: a shank portion gripped by a main shaft; a tool attachment portion having an insertion port into which a tool is inserted in a tip end surface thereof; a cover having a tubular wall that covers an outer periphery of the tool attachment portion and a bottom surface that covers the tip end surface of the tool attachment portion; a bearing provided between the tubular wall of the cover and the tool attachment portion; and a stopper that prevents the cover from co-rotating with the tool attachment portion. A through hole penetrated by the tool and an ejection port disposed on a periphery of the through hole in order to eject the coolant toward the tool are provided in the bottom surface of the cover.