To provide a power semiconductor device equipped with a circuit breaking mechanism having a thermal fuse fusible at low temperatures while having a small resistance value.

This circuit breaking mechanism 10 includes: one primary wiring conductor 2 and the other primary wiring conductor 2 provided on the upper side of a substrate 1 and each connected to a prescribed electronic circuit; and heater conductors 4 provided on the primary surface of the substrate 1 so as to generate heat when a current flows in it. The circuit breaking mechanism 10 also includes one low-melting point metal conductor 5 for connecting the one primary wiring conductor 2 to an electrode film 3, and the other low-melting point metal conductor 5 for electrically connecting the other primary wiring conductor 2 to the electrode film 3. Each of the one low-melting point metal conductor 5 and the other low-melting point metal conductor 5 has a melting point lower than that of either of the one primary wiring conductor 2 and the other primary wiring conductor 2.