Each of first and second pole cores has a boss portion, six core flange portions; and six claw-shaped magnetic pole portions, the first and second pole cores being disposed such that the claw-shaped magnetic pole portions face each other so as to intermesh and leading end surfaces of the boss portions are abutted with each other. The boss portions include coil mount portions in which cross-sectional shapes that are perpendicular to the central axis are hexagons; and abutted portions that have circular cross sections and that are disposed so as to protrude from leading ends of the coil mount portions. Radially-inner surfaces of the claw-shaped magnetic pole portions face side surfaces of the coil mount portions and are parallel to the side surfaces of the coil mount portions at the cross sections that are perpendicular to the central axis.