Abstract: A fastener for a belt includes a buckle member adapted to be attached to a first end portion of the belt, wherein the buckle member includes a receiving member having an opening for receiving the belt therethrough, an operating plate provided with a tongue and pivotally mounted to the receiving member, the tongue extending from the operating plate toward a rear portion of the receiving member, and a fixing member pivotally fixed at the rear portion of the receiving member; and a slot member including a plurality of slots and protrusions and adapted to be formed to a second end portion of the belt, wherein the tongue is inserted into one of the slots and abutted against a substantially vertical surface of one of the protrusions by the operation of the operating plate.