Abstract: Apparatus for detachably mounting molds on die plates of, for example, a die casting machine, which comprises a casing slidable on the die plate, a wedge member located within the casing and in contact with the inner surface thereof and a clamp lever located in the casing to be rotatable about a shaft attached to the casing and in contact with the inclined surface of the wedge member at one end. A clamping member to clamp a mold half in the die plate is provided for the other end of the clamp lever. The wedge member and the casing are moved by a hydraulic drive engaged with the wedge and there is provided a member for resiliently urging the one end of the clamp lever against the inclined surface of the wedge member.