A rotation restricting mechanism is provided between a mounting shaft section of a rotational shaft and a mounting tube section of a rotary atomizing head. The rotation restricting mechanism includes a male spline member provided on the outer peripheral side of the mounting shaft section, and a female spline member provided on the inner peripheral side of the mounting tube section. By meshing engagement of the male spline member with the female spline member, the rotation restricting mechanism restricts rotational displacements of the rotary atomizing head relative to the rotational shaft.