An induction motor having a reverse-rotation preventing function, comprises: a stator provided with a winding coil generating flux by a current; an induction rotor provided with a cage and rotatably inserted in the stator, wherein a rotary shaft is coupled to its inside; a synchronous rotor provided with a permanent magnet and rotatably coupled between the stator and the induction rotor; an induction-force generating unit generating a force for moving the synchronous rotor in an axial direction; and a rotation preventing unit preventing a reverse rotation by fixing the synchronous rotor moved by the induction-force generating unit at the time of reverse rotation of the synchronous rotor. When a reverse rotation of the induction motor occurs as a reverse-rotation force is applied to the induction rotor due to a phase of a voltage which is initially applied and an unparallel rotating magnetic field at the time of initial driving of the motor, the load inertia of the synchronous rotor is increased, and the reverse rotation of the synchronous rotor and the induction rotor is prevented. Also, the construction for preventing the reverse rotation of the motor is simplified, and a small number of components are required.