A coil sub-assy includes a coil plate which has an insulating film attached to at least one side thereof and an “I”-shaped portion to be inserted into a slot of a stator core. The plurality of coil plates forming coils of an identical phase are laminated in a thickness direction of the “I”-shaped portion. The coil plates opposite to each other are formed such that a shortest distance between end faces of the “I”-shaped portions in a width direction is longer than a shortest distance between end faces of the “I”-shaped portions in the thickness direction.