An alloy type thermal fuse is provided in which a Bi--Sn alloy is used as a fuse element, which has an operating temperature of about 140.degree. C., which, even when used at a high power, can safely operate, and in which dispersion of the operating temperature can be sufficiently reduced. Also a material for a thermal fuse element is provided.An alloy composition in which Bi is larger than 50% and 56% or smaller, and a balance is Sn is used as a fuse element of the alloy type thermal fuse.