A motor driving system comprising: a motor angle detection circuit that receives a motor angle signal to detect a motor angle that is the angle of a rotor of a motor; a current detection circuit that receives a motor current signal to detect a motor current value that is the value of a current for driving the motor; a mobile object inclination angle detection circuit that receives an inclination angle signal to detect a mobile object inclination angle that is the inclination angle of a mobile object that moves by driving the motor; a motor control circuit that outputs a control signal for controlling the driving of the motor; and a failure detection circuit that detects a failure of the motor angle detection circuit to output a failure detection signal; a storage apparatus; a learning control circuit adapted, during a normal state, to store, in the storage apparatus, motor current values, control signals, and mobile object inclination angles in an associated manner; and a control signal generator, characterised in that said control signal generator is configured to obtain, upon receipt of the failure detection signal, a motor current value from the current detection circuit and a mobile object inclination angle from the mobile object inclination angle detection circuit, obtain from the storage apparatus a stored control signal that is associated with the obtained motor current value and the obtained mobile object inclination angle, and output a setting value for causing the motor control circuit, upon receipt of the setting value, to output a control signal having a waveform similar to that of the obtained control signal. a motor angle detection circuit that receives a motor angle signal to detect a motor angle that is the angle of a rotor of a motor; a current detection circuit that receives a motor current signal to detect a motor current value that is the value of a current for driving the motor; a mobile object inclination angle detection circuit that receives an inclination angle signal to detect a mobile object inclination angle that is the inclination angle of a mobile object that moves by driving the motor; a motor control circuit that outputs a control signal for controlling the driving of the motor; and a failure detection circuit that detects a failure of the motor angle detection circuit to output a failure detection signal; a storage apparatus; a learning control circuit adapted, during a normal state, to store, in the storage apparatus, motor current values, control signals, and mobile object inclination angles in an associated manner; and a control signal generator, characterised in that said control signal generator is configured to obtain, upon receipt of the failure detection signal, a motor current value from the current detection circuit and a mobile object inclination angle from the mobile object inclination angle detection circuit, obtain from the storage apparatus a stored control signal that is associated with the obtained motor current value and the obtained mobile object inclination angle, and output a setting value for causing the motor control circuit, upon receipt of the setting value, to output a control signal having a waveform similar to that of the obtained control signal.