A stator manufacturing method includes the steps of preparing an armature core, forming an insulating member including two opposing portions from a sheet-like insulating material, and deforming the insulating member to move the two opposing portions toward each other. The method also includes the step of inserting distal parts of the two opposing portions into the corresponding slit from the axial direction thereby covering an inner surface of each of the slot with the insulating member. Further, the method includes the steps of inserting a conductor forming a winding into each of the slots between the two opposing portions.