To provide a thermal fuse built-in resistor applicable for two circuits.

The thermal fuse built-in resistor houses a first resistor 1, a second resistor 2, and a piece of thermal fuse 3 in a case 4, and is constituted by arranging the thermal fuse 3 between the first resistor 1 and the second resistor 2. The includes: a first lead wire 5 extended outside the case 4 from the first resistor 1; a second lead wire 6 extended outside the case 4 from the second resistor 2; and a third lead wire 7 extended in a direction opposite to the case 4 from the first resistor 1.