According to a power semiconductor device of the present invention, it comprises a plurality of lead frames formed into like a wiring pattern, a power semiconductor element joined onto the lead frame, and a capacitor placed between mutually adjacent two lead frames, and is encapsulated with a mold resin. The capacitor is characterized in that external electrodes of that capacitor are connected to the lead frames each through a stress-relaxation structure portion that is lower in rigidity than the capacitor.