An electric power steering apparatus (1) is provided with a heat sink (5) and an intermediate member (4) whose surface portions are perpendicularly placed with respect to an axial direction of a motor's shaft center, and arranged in such a way that each of power modules (51a, 51b) of a plurality of driving circuits is attached on a surface portion of the heat sink (5) so that an extending direction of a maximum outer dimension of the power modules (51a, 51b) is perpendicular to the axial direction, and each of electric devices (C1a-C1b) of the plurality of driving circuits is attached on a surface portion of the intermediate member (4) so that an extending direction of a maximum outer dimension of the electric devices (C1a-C1b) is perpendicular to the axial direction.