A clamp includes a base plate that is locked to an adhesive sheet which covers and holds an electric wire, a shaft that projects from the base plate and is inserted through an attaching hole which is bored through the adhesive sheet, an engaging portion that is formed at the distal end of the shaft, is inserted through the attaching hole and is engaged with an engaging hole of an attached body, and fixing pieces that project from the base plate to have an interval between projecting ends of the fixing pieces which is larger than the maximum opening width of the attaching hole, and hold and fix the fringe of the attaching hole with the base plate.