In a power module having two systems of inverter circuits for driving an electric motor of a motorized equipment, a wiring board mounted with power transistors and shunt resistances is embedded in a plate-like mold section. A plurality of lands have radiation surfaces exposed from the mold section. The radiation surfaces of a first land row constituted by a first group of the lands are provided on the same plane and the same straight line, and the radiation surfaces of a second land row constituted by a second group of the lands are provided on the same plane and the same straight line. The radiation surfaces of the first and second land rows are in surface-to-surface contact with a heat sink through insulation radiation sheets to dissipate a heat generated by the power module.