In the present invention, an insertion groove open radially inward of a stator iron core is provided along the axial direction of the stator iron core in a tubular-section-overlaying section overlaying the inner circumferential surface of the tubular section of the stator iron core. An inter-coil insulator disposed between multiple stator coils has a groove insertion section. The groove insertion section has a first insertion section capable of being inserted into the insertion groove from the lengthwise-direction end section of the insertion groove in a state in which an insulating film is folded, and a second insertion section connected to the first insertion section in the direction in which the groove insertion section is inserted into the insertion groove and having a cross section with an outline different from that of the first insertion section. The second insertion section generates a stronger elastic restoring force than the first insertion section in a state where the groove insertion section has been inserted into the insertion groove.