A device for preventing an accelerator from being erroneously operated when an accelerator pedal of a motor vehicle is erroneously pushed down includes a magnetic coupling device comprising an accelerator interlocking member interlocking with an accelerator pedal and a throttle interlocking member connected to a throttle cable. When the accelerator pedal is pushed down during normal operation the throttle cable is operated through the magnetic coupling device to cause the motor vehicle to be accelerated. When the accelerator pedal (14) is erroneously pushed down in spite of the brake pedal being intended to be pushed down, the magnetic coupling device decouples and prevents the throttle valve from being operated and the motor vehicle from being accelerated.