The invention provides a thermal fuse and a fuse element of the low-melting fusible alloy type in which the fuse element has an alloy composition of 37 to 43% In, 10 to 18% Sn, and the balance Bi. As a result, the operating temperature is in the range of 65 to 75° C., requests for environment conservation can be satisfied, the diameter of the fuse element can be made very thin or reduced to about 300 μmφ, self-heating can be suppressed, and the thermal stability can be satisfactorily guaranteed.