A rotor includes a rotor core and a rotor shaft. The rotor shaft includes an insertion portion, an external thread portion, a key groove and a nut. The insertion portion is inserted into a cylindrical hole of the rotor core. The external thread portion extends from the insertion portion to an outer side in an axial direction of the rotor shaft. The external thread portion has a plurality of thread ridges formed on an outer peripheral surface. The key groove is provided on an outer peripheral surface of the rotor shaft so as to extend in the axial direction from the external thread portion through the insertion portion. The nut is screwed onto the external thread portion, and has a crimped portion formed so as to enter the key groove.