To provide a thermosensitive pellet type thermal fuse having a high thermal response speed to a temperature control object with a plane part, and its manufacturing method, and an installation method.

In the thermal fuse, a thin narrow case 11 having a hollow portion inside includes a plane part 11e which surface contacts the plane part of a temperature control object, and also includes a first lead wire 12 and a second lead wire 13 arranged along the length direction of the thin and long case 11, and a movable contact 16 which is arranged in the hollow part and is in contact with the second lead wire always energized in separation direction through a molten pellet 15 arranged in contact with the first lead wire 12.