To provide a method in which an alloy type thermal fuse of which the melting point of the fuse element is lower than a reflow or flow soldering temperature can be mounted safely by the reflow or flow soldering method.

This is a conjugate alloy type thermal fuse in which a flux composition containing wax or a polymer compound is used as a flux 4 of an alloy type thermal fuse, and the wax or polymer compound in the flux composition is separated from the alloy type thermal fuse, and by this separated object, contact of the fuse element 3 and the flux remaining component 4b is cut off, and the fuse element can be maintained in non-melting state by reflow or flow soldering. This conjugate alloy type thermal fuse is mounted by reflow or flow soldering and the separated object of the conjugate alloy type thermal fuse is melted and mixed to the flux remaining component.