To provide a self-retention thermally-actuated switch excellent in assembly performance and capable of being miniaturized.

The switch has an insulating base 1; a first and a second fixed terminals 2, 3 each with one part exposed to the base 1; a reversible bimetal piece 5 of which one end side is connected to the first fixed terminal 2 and the other side is firmly fixed to a movable contact 6; a fixed contact 3a fitted to the second fixed terminal 3 and contacting with and separating from the movable contact 6; and a positive temperature coefficient thermistor 4 disposed near the bimetal piece 5 and retaining reverse of the bimetal piece 5 by generation of heat in accordance with passing electricity. Projecting pieces 2a, 3c extending in a direction approaching the bimetal piece 5 are formed at the first and the second fixed terminals 2, 3, the thermistor 4 is disposed between the projecting pieces 2a, 3c and the thermistor 4 is connected in parallel between the first and the second fixed terminals 2, 3.