A motor rotational angle detection device comprising: a plurality of motor rotational angle detection units (6, 7) configured to detect a rotational angle of a motor, wherein said plurality of motor rotational angle detection units (6, 7) 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 (6, 7) configured to detect a rotational angle of a motor, wherein said plurality of motor rotational angle detection units (6, 7) 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.