An electric power conversion apparatus includes at least one semiconductor module, a capacitor, a pair of positive and negative busbars and an insulator. The positive busbar includes a positive busbar base protruding from the capacitor in a Y direction and at least one positive busbar terminal extending perpendicular to an X direction. The negative busbar includes a negative busbar base protruding from the capacitor in the Y direction and at least one negative busbar terminal extending perpendicular to the X direction. The positive and negative busbar bases are arranged to have their major surfaces facing each other in a Z direction. The positive and negative busbar terminals at least partially overlap each other in the X direction with the insulator interposed therebetween. The at least one semiconductor module has a pair of positive and negative power terminals connected respectively to the positive and negative busbar terminals.