To provide a fusible alloy type thermal fuse which is free from harmful metals causing environmental problems and in which operating temperature can be set at a temperature in a high temperature region not lower than 190°C.

The fusible alloy type thermal fuse is constituted in such a way that: a low melting-point fusible alloy 3 is connected to a couple of lead members 1 and 2 by resistance welding; a flux film 4 is formed on the surface of the low melting-point fusible alloy 3; and then the low melting-point fusible alloy 3 is held in an insulating vessel or case 5 of ceramic insulating tube of alumina etc. As the low melting-point fusible alloy 3, the low melting point fusible alloy 3 in which either of the following alloys (1) and (2) is used and which can be operated with certainty at 190 to 210°C operating temperature is selected: (1) a ternary alloy which has a composition consisting of, by weight, 3.0 to 4.0% Ag, 6.0 to 10.0% In and the balance Sn and is free from harmful metals; (2) a quaternary alloy prepared by adding Bi to the above (1). Further, the flux film 4 is formed using a specified coating material.