An electric drive device has a motor housing accommodating therein an electric motor; a pair of supporting stems arranged so as to face to each other on an end surface, which is an opposite side to an output shaft portion of a rotation shaft of the electric motor, of the motor housing and extending in a direction of the rotation shaft which is an opposite direction to the output shaft portion; a heat radiation base body arranged between the pair of supporting stems and extending in the same direction as those of the supporting stems; fixing bolts screwed into the heat radiation base body from a radially outer side to a radially inner side through the supporting stems and connecting the supporting stems and the heat radiation base body; one electronic control unit of a redundant system, arranged along a direction in which the heat radiation base body extends and having a board that is fixed to the heat radiation base body with thermal conduction to the heat radiation base body allowed; and the other electronic control unit of the redundant system, arranged along a direction in which the heat radiation base body extends and having a board that is fixed to the heat radiation base body with thermal conduction to the heat radiation base body allowed.