A motor drive device (10, 10A, 10B) configured to drive a motor using a three-phase alternating current as a power source, the motor drive device (10, 10A, 10B) comprising: a rectifier circuit configured to rectify the three-phase alternating current to generate a rectified current; a current detection circuit configured to detect the rectified current; a cross point detection circuit (13, 13A, 13B) configured to detect a cross point between the rectified current detected by the current detection circuit and a predetermined current value, and to output a control signal indicating whether or not to drive the motor; and a smoothing circuit configured to smooth the rectified current and to generate a smoothed current; wherein the cross point detection circuit (13, 13A, 13B) is configured to output the control signal indicating that the motor is not to be driven in a case where a number of times of the detection of the cross point in one cycle of the three-phase alternating current is 2, the cross point detection circuit (13, 13A, 13B) is further configured to output the control signal indicating that the motor is to be driven, in a case where a voltage of the smoothed current is equal to or higher than the minimum of a voltage of the rectified current and where the number of times of the detection of the cross point in one cycle of the three-phase alternating current is 6, and the cross point detection circuit (13, 13A, 13B) is further configured to output the control signal indicating that the motor is to be driven, in a case where the voltage of the smoothed current is lower than the minimum of the voltage of the rectified current and where the number of times of the detection of the cross point in one cycle of the three-phase alternating current is 0. a rectifier circuit configured to rectify the three-phase alternating current to generate a rectified current; a current detection circuit configured to detect the rectified current; a cross point detection circuit (13, 13A, 13B) configured to detect a cross point between the rectified current detected by the current detection circuit and a predetermined current value, and to output a control signal indicating whether or not to drive the motor; and a smoothing circuit configured to smooth the rectified current and to generate a smoothed current; wherein the cross point detection circuit (13, 13A, 13B) is configured to output the control signal indicating that the motor is not to be driven in a case where a number of times of the detection of the cross point in one cycle of the three-phase alternating current is 2, the cross point detection circuit (13, 13A, 13B) is further configured to output the control signal indicating that the motor is to be driven, in a case where a voltage of the smoothed current is equal to or higher than the minimum of a voltage of the rectified current and where the number of times of the detection of the cross point in one cycle of the three-phase alternating current is 6, and the cross point detection circuit (13, 13A, 13B) is further configured to output the control signal indicating that the motor is to be driven, in a case where the voltage of the smoothed current is lower than the minimum of the voltage of the rectified current and where the number of times of the detection of the cross point in one cycle of the three-phase alternating current is 0.