An n-type region encloses an n-type well region is disclosed in which is disposed a high-side drive circuit. A high resistance polysilicon thin film configuring a resistive field plate structure of a high breakdown voltage junction termination region is disposed in spiral form on the n-type region. An OUT electrode, a ground electrode, and a Vcc1 electrode are disposed on the n-type region. The Vcc1 electrode is connected to the positive electrode of an auxiliary direct current power supply (a bootstrap capacitor). The OUT electrode is connected to the negative electrode of the auxiliary direct current power supply. One end portion (a second contact portion) of the high resistance polysilicon thin film is connected to the ground electrode, and the other end portion (a first contact portion) of the high resistance polysilicon thin film is connected to the OUT electrode.