A material of the stator core is different from a material of the housings, in a state where one end portion in the axis direction of the stator core is contacted to the first housing, and the other end portion in the axis direction of the stator core is contacted to the second housing; and a neighboring portion of a contact portion, at which the first housing is contacted to the stator core, and another neighboring portion of a contact portion, at which the second housing is contacted to the stator core, are connected by a connecting component in the axis direction, of which material is the same as a material of the stator core, whereby the first housing and the second housing are connected each other; and the first housing and the second housing face each other in a state where a gap intervenes between both housings.