A heat sink is provided on a motor. A power module is provided on the heat sink to switch current supply to motor coils. A control circuit substrate is arranged on the heat sink and connected electrically to the power module. A power circuit substrate is connected electrically to the power module and arranged at an opposite side of the control circuit substrate relative to the heat sink. A control circuit connector is electrically connected to the control circuit substrate. A power circuit connector is electrically connected to the power circuit substrate. The control circuit connector and the power circuit connector are arranged between the control circuit substrate and the power circuit substrate.