An stator manufacturing apparatus including an substantially cylindrically-shaped insertion jig from which the rectangular wire is axially detachable, and having protrusions respectively provided at positions aligned with the slots on an outer peripheral surface thereof to protrude radially, and one end-side restricting members respectively provided at positions offset from the protrusions formed in the circumferential direction on an inner diameter side of an inscribed circle of teeth each located between adjacent ones of the slots so as to protrude toward one axial end side. With the linear portions and the slots being aligned with each other, the insertion jig is inserted into the stator core from the one end side of the insertion jig, and is removed from the stator core toward the other end side, so as to respectively dispose the linear portions at predetermined positions in the slots.