A motor drive device comprising: a general drive controller configured to control a motor unit configured to drive a wheel of an electric vehicle depending on a position of magnetic poles by using an angle detection value sensed by a motor rotor angle sensor provided at the motor unit; a first motor rotor angle estimator configured to estimate an angle of a motor rotor of the motor unit without using a rotation sensor; a second motor rotor angle estimator configured to estimate an angle of the motor rotor from a detection signal sensed by a wheel rotational frequency sensor configured to sense a rotation speed of the wheel driven by the motor unit; a sensor malfunction determiner configured to determine a malfunction of the motor rotor angle sensor; and a sensor switcher configured to cause the general drive controller to perform control using an estimation value of the motor rotor angle estimated by the first or second motor rotor angle estimator instead of the angle detection value sensed by the motor rotor angle sensor once the sensor malfunction determiner determines that the motor rotor angle sensor malfunctions, wherein the sensor malfunction determiner is further configured to determine a malfunction of the wheel rotational frequency sensor, and the sensor switcher is configured to cause the general drive controller to perform control using an estimation value of the motor rotor angle estimated by the second motor rotor angle estimator once the sensor malfunction determiner determines that the motor rotor angle sensor malfunctions, and the sensor switcher is configured to cause the general drive controller to perform control using an estimation value of the motor rotor angle estimated by the first motor rotor angle estimator once the sensor malfunction determiner determines that both the motor rotor angle sensor and the wheel rotational frequency sensor malfunction. a general drive controller configured to control a motor unit configured to drive a wheel of an electric vehicle depending on a position of magnetic poles by using an angle detection value sensed by a motor rotor angle sensor provided at the motor unit; a first motor rotor angle estimator configured to estimate an angle of a motor rotor of the motor unit without using a rotation sensor; a second motor rotor angle estimator configured to estimate an angle of the motor rotor from a detection signal sensed by a wheel rotational frequency sensor configured to sense a rotation speed of the wheel driven by the motor unit; a sensor malfunction determiner configured to determine a malfunction of the motor rotor angle sensor; and a sensor switcher configured to cause the general drive controller to perform control using an estimation value of the motor rotor angle estimated by the first or second motor rotor angle estimator instead of the angle detection value sensed by the motor rotor angle sensor once the sensor malfunction determiner determines that the motor rotor angle sensor malfunctions, wherein the sensor malfunction determiner is further configured to determine a malfunction of the wheel rotational frequency sensor, and the sensor switcher is configured to cause the general drive controller to perform control using an estimation value of the motor rotor angle estimated by the second motor rotor angle estimator once the sensor malfunction determiner determines that the motor rotor angle sensor malfunctions, and the sensor switcher is configured to cause the general drive controller to perform control using an estimation value of the motor rotor angle estimated by the first motor rotor angle estimator once the sensor malfunction determiner determines that both the motor rotor angle sensor and the wheel rotational frequency sensor malfunction.