PURPOSE: To relax the stress of a bar end section, and to shorten axial length by mounting a cushioning material absorbing the displacement of an end ring to a connecting section between a rotor bar and the end ring.

CONSTITUTION: In a rotor with a rotor bar 30 and an end ring 40 short-circuiting the end section of the rotor bar 30, a cushioning material 50 for absorbing the heat of the end ring 40 and displacement by centrifugal force, etc. is interposed to a connecting section between the rotor bar 30 and the end ring 40. Accordingly, a stress working to the rotor bar 30 is reduced, thus shortening a bar end section is size in the rotor bar 30.