To provide a method for discriminating an abnormality of a torque sensor of an electric power assisted bicycle for restraining the deterioration of travelling performance caused by an assist interruption and discriminating the abnormality of the torque sensor so as to carry out an appropriate assist stopping process.

The electric power assisted bicycle comprises the torque sensor 41 for detecting a force on pedal to rotate/drive pedals, an assistance motor 42 for assisting the force on pedal, a controller for controlling a drive current of the motor 42 according to an output of the torque sensor 41, and a torque sensor discriminating means 52 for discriminating a normality/abnormality of the torque sensor 41 synchronizing pedal rotation while traveling based on the output of the torque sensor which fluctuates repeating an upper peak value and a bottom value or a zero point value of the torque sensor while stopping. The electric power assisted bicycle interrupts the assist by the motor 42 when the torque sensor discriminating means 52 detects the abnormality of the output of the torque sensor while traveling or stopping. In the abnormality discriminating method for the torque sensor of the electric power assisted bicycle, when the number of times of assist interruptions by the motor 42 consecutively reaches the predetermined number of times, the torque sensor 41 itself is determined to be abnormal and an error display is given while the assist by the motor 42 is stopped.