In a motor drive apparatus for driving a three-phase AC motor, a first mounting part of a heat sink is formed along an end. A second mounting part is formed in a direction perpendicular to the first mounting part and includes a first column part and a second column part. Three motor relay FETs are mounted on the first mounting part. Six inverter FETs and two power relay FETs are mounted on the second mounting part. Leads of the FETs are electrically connected to an electric circuit substrate. Heat generated by the FETs is radiated to the heat sink through an insulating and heat radiating sheet. By thus arranging the FETs, the motor drive apparatus is reduced in size.