To provide a thermal fuse using a low melting point metal temperature-sensitive material not containing hazardous metal such as Pb, Cd, Hg or the like and having a long-term reliability with an operation temperature of 250°C or higher.

A fixed contact 15 and a movable contact 16 are mounted on one end of lead members 12, 13 engaged in a groove portion of an insulation supporting member 11; the fixed contact 15 is provided with a supporting part with a tip end portion extending from the one lead member 12 mold-processed and a contact part is formed on this; and the movable contact 16 is provided with a contact part on a tip end portion of an elastic member 17 caulked and fixed by a rivet 14 together with the other lead member 13. A low melting point metal temperature-sensitive material 20 of a Bi system or a Zn system having an operation temperature of 250°C or higher is housed in a circular-shaped deep groove 18 formed almost at the center of the insulation supporting member 11 in a state of a part or a whole directly contacting with the outside air.