An electric power converter is provided with: a power semiconductor module, which has a power semiconductor element that converts a direct current into an alternating current; a capacitor module, which has a capacitor element that smooths the direct current; and a cooling body, which cools the power semiconductor module and the capacitor module. The capacitor module has: a case, which has an approximately rectangular shape, has an opening formed in one surface, and has a space for housing the capacitor element; and a DC conductor for electrically connecting the power semiconductor element and the capacitor element to each other. The cooling body is formed to face the bottom surface on the inner wall of the case, and both the side surfaces of the case, the side surfaces facing each other. Between the capacitor element and the inner wall surfaces of the case, the direct current conductor is formed along the bottom surface and both the side surfaces of the case.