A method of manufacturing a rotor of an electric motor, the rotor including a laminated core of multi-layer structure formed from electromagnetic thin plates laminated in an axial direction of a rotational shaft, and a pair of end plates disposed on opposite sides in the axial direction of the laminated core, and the rotor being rotatably disposed in an inside of a stator, the method including: fitting the rotational shaft into an insertion hole formed in a center region of the end plates having elasticity in a direction of plate thickness; positioning the end plates at specified position on the rotational shaft; and abutting either one of the end plates in elastically deformed state to at least one end of the laminated core.