A casing houses: semiconductor modules constituting a main circuit for power conversion; a capacitor electrically connected to the main circuit; drive circuits that provide the main circuit with a drive signal used in power conversion operation; a control circuit that provides the drive circuit with a control signal used to prompt the drive circuit to provide the drive signal. Within the casing, a cooling chamber including a coolant passage is formed, and a chamber wall of the cooling chamber is formed with a thermally conductive material. At least the semiconductor modules are housed inside the cooling chamber, and at least the capacitor and the control circuit are disposed outside the cooling chamber.