A motor rotational angle detection device comprising: a plurality of motor rotational angle detection units configured to detect a rotational angle of a motor , wherein said plurality of motor rotational angle detection units comprises a main rotation sensor configured to detect a rotational angle of the motor and a sub-rotation sensor configured to detect a rotational angle of the motor ; the motor rotational angle detection device further comprising: a normal angle decision device comprising a redundant rotation sensor adapted to obtain a motor rotational angle information item; the normal angle decision device being configured to decide a normal motor rotational angle; the motor rotational angle detection device being characterized in that : the normal angle decision device is configured to detect a difference between the output values of the main rotation sensor and the sub-rotation sensor , and, when a difference is detected between output values of the main rotation sensor and the sub-rotation sensor , to respectively compare the output value of each of the main rotation sensor and the sub-rotation sensor with the motor rotational angle information item obtained from the redundant rotation sensor , to identify the motor rotational angle detection unit providing the smallest difference as the normal motor rotational angle detection unit, and to decide the normal motor rotational angle. a plurality of motor rotational angle detection units configured to detect a rotational angle of a motor , wherein said plurality of motor rotational angle detection units comprises a main rotation sensor configured to detect a rotational angle of the motor and a sub-rotation sensor configured to detect a rotational angle of the motor ; the motor rotational angle detection device further comprising: a normal angle decision device comprising a redundant rotation sensor adapted to obtain a motor rotational angle information item; the normal angle decision device being configured to decide a normal motor rotational angle; the motor rotational angle detection device being characterized in that : the normal angle decision device is configured to detect a difference between the output values of the main rotation sensor and the sub-rotation sensor , and, when a difference is detected between output values of the main rotation sensor and the sub-rotation sensor , to respectively compare the output value of each of the main rotation sensor and the sub-rotation sensor with the motor rotational angle information item obtained from the redundant rotation sensor , to identify the motor rotational angle detection unit providing the smallest difference as the normal motor rotational angle detection unit, and to decide the normal motor rotational angle. a normal angle decision device comprising a redundant rotation sensor adapted to obtain a motor rotational angle information item; the normal angle decision device being configured to decide a normal motor rotational angle; the motor rotational angle detection device being characterized in that : the normal angle decision device is configured to detect a difference between the output values of the main rotation sensor and the sub-rotation sensor , and, when a difference is detected between output values of the main rotation sensor and the sub-rotation sensor , to respectively compare the output value of each of the main rotation sensor and the sub-rotation sensor with the motor rotational angle information item obtained from the redundant rotation sensor , to identify the motor rotational angle detection unit providing the smallest difference as the normal motor rotational angle detection unit, and to decide the normal motor rotational angle. <EOS>