A rotating electric machine comprises a stator and a rotor. In the rotor, numerous slots are formed along a circumferential direction. In the each of slots, a first stator coil and a second stator coil are inserted and insulated by an insulator inserted before inserting the coils in the slots. The insulator encircles the first and second stator coils so as to be formed into an S shape. The center portion thereof extends over the area between the first and second stator coils. One end of the insulator is held between one surface of the center portion of the insulator and the first stator coil. Other end of the insulator is held between another surface of the center portion of the insulator and the second stator coil.