The stator of the electric motor comprises: a stator core; tooth sections being radially extended from the stator core; an even number of slots, each of which is formed between the tooth sections; an insulator covering the tooth sections; and motor coils being wound in the slots. The insulator has guide projections, each of which corresponds to each of the tooth sections so as to guide a magnet wire. The guide projections have guide sections, each of which includes a base end part and a front end part. In each of the guide sections, a radial thickness of at least one part located in the base end part is thin, a radial thickness of the front end part is thicker than that of the base end part. The guide sections are formed in same side faces of the guide projections arranged in the circumferential direction.