Abstract: A power inverter having high reliability in a severe use environment with reduced delay in switching times and rounding of waveforms. Specifically, the power inverter utilizes switching element drive and protection circuits, and a control arithmetic unit (CAU) formed on a single substrate through a high-voltage integrated circuit. Additionally, the ground potentials (GND) of the switching element drive and protection circuits, and the CAU are made equal to the ground potentials of the switching elements and the power inversion portion of the circuit. Finally, the power inversion portion and a smoothing capacitor are constructed using the same module as the substrate.