To provide the rotor of an induction motor, in which rotor bars can be inserted into slots easily, the eigenvalue of the torsional vibration of a short- circuit ring is increased to avoid resonance and the mechanism strength is increased to avoid the damages of the rotor bars by a method, wherein the rotor bars are fixed to the rotor core at one side end surfaces of the slots of the rotor core.

When a rotor bar 11 is inserted into a slot 10, if the one side corner part 11A of the rotor bar 11 is ppressed against a pressing means 15, for instance an inclined plane 15A, the rotor bar 11 is brought into contact with the one side surface 10D of the slot over approximately the entire surface by the inclined plane 15A to increase the contact area between the rotor bar 11 and the one side surface 10D of the slot and, corresponding to the increase of the mechanical strength, the oscillation frequency is increased, resonance can be avoided and distortion between the rotor bar 11 and a short-circuit ring can be reduced, so that breakage between the rotor bar 11 and the short- circuit ring can be avoided.