An electric motor diagnosing apparatus is provided in a vehicle having a generator driven by a drive torque of a drive source, an electric motor driven by electric power supplied from the generator, and a wheel driven by the electric motor. The electric motor diagnosing apparatus comprises a counterelectromotive force determining section and an electric motor diagnosing section. The counterelectromotive force determining section determines whether a voltage of electric power supplied from the generator to the electric motor is greater than an induced voltage of a counterelectromotive force of the electric motor. The electric motor diagnosing section drives the electric motor by controlling the generator to supply the electric power to the electric motor, and determines whether the electric motor is rotating, upon determining that the voltage of the electric power supplied from the generator to the electric motor is greater than the electric motor induced voltage.