A guide wire holder includes a sheath having a lumen, an operation wire which is inserted through the lumen to be able to advance and retract, and a hook which is continuous with a distal end of the operation wire and protrudes from a distal end of the sheath, wherein the sheath has an inner wall surface which forms a groove configured to extend from the distal end of the sheath to a proximal end side of the sheath, the groove has an opening portion which opens to an outer peripheral surface of the sheath, the hook has a guide wire engagement surface which is engageable with a guide wire, and the guide wire is able to be held between the guide wire engagement surface and the inner wall surface.