Discloses is a motor for an environmentally friendly vehicle. In particular, the motor includes a stator core including a first coating portion and a second coating portion. The first portion and the second coating portion are adjacent to each other, wound with a coil on an outside thereof and fixedly installed in a motor case and the first coating portion is thinner than the second coating portion. The motor also includes a rotor core configured to move between the first coating portion and the second coating portion depending upon a speed of the motor. A controller is configured to control an operation of an actuator to move the rotor between the first coating portion and the second coating portion to maximize the efficiency of the motor depending upon the speed of the motor.