A stapler is provided, including: a main body, including a front end portion, the front end portion including a staple outlet and a plate member, the plate member including a concave adjacent to the staple outlet; a holder, switchably disposed on the main body, including a plurality of notches with different sizes and a plurality of first positioning portions; and a positioning member, disposed on the main body, releasably positioned with one of the plurality of first positioning portions so that one of the plurality of notches corresponds to the concave in a front to rear direction, for receiving a portion of a cable.