To stably operate a thermoswitch so as to respond satisfactorily even in use with any layout.

The thermoswitch 209 includes: a bimetal 3 (3-1 and 3-2) deformed when exceeding a critical temperature; a cap member 7 that transmits heat to the bimetal 3 from outside; an inner lid 2 accommodating the bimetal 3 in a space formed between the cap member 7 and this inner lid 2; and a guide pin 6 pressed by the deformed bimetal 3 and moved to stop the electrical connection of an electric contact part, wherein the bimetal 3 is fixed to neither the cap member 7 nor the inner lid 2. The thermoswitch 209 further includes a coil spring 8 that biases the bimetal 3 against the cap member 7.