A motor control unit that supplies three-phase alternating currents to a motor by controlling switching of pairs of transistors provided in an inverter circuit, that detects, using current sensors, values of the phase currents that are supplied to the motor, and that determines whether a through-current has occurred in the pairs of transistors based on the detected phase current values, wherein: a first threshold is set for the phase current values; a second threshold is set for a sum of the phase current values; and it is determined whether a through-current has occurred in the transistors based on a comparison between each of the phase current values and the first threshold and a comparison between the sum of the phase current values and the second threshold, wherein: the comparison between each of the phase current values and the first threshold is made by determining whether at least one of absolute values of the phase current values is larger than or equal to the first threshold; the comparison between the sum of the phase current values and the second threshold is made by determining whether an absolute value of the sum of the phase current values is larger than or equal to the second threshold; and it is determined that a through-current has occurred in the transistors when both a condition that at least one of the absolute values of the phase current values is larger than or equal to the first threshold and a condition that the absolute value of the sum of the phase current values is larger than or equal to the second threshold are satisfied. a first threshold is set for the phase current values; a second threshold is set for a sum of the phase current values; and it is determined whether a through-current has occurred in the transistors based on a comparison between each of the phase current values and the first threshold and a comparison between the sum of the phase current values and the second threshold, wherein: the comparison between each of the phase current values and the first threshold is made by determining whether at least one of absolute values of the phase current values is larger than or equal to the first threshold; the comparison between the sum of the phase current values and the second threshold is made by determining whether an absolute value of the sum of the phase current values is larger than or equal to the second threshold; and it is determined that a through-current has occurred in the transistors when both a condition that at least one of the absolute values of the phase current values is larger than or equal to the first threshold and a condition that the absolute value of the sum of the phase current values is larger than or equal to the second threshold are satisfied. the comparison between each of the phase current values and the first threshold is made by determining whether at least one of absolute values of the phase current values is larger than or equal to the first threshold; the comparison between the sum of the phase current values and the second threshold is made by determining whether an absolute value of the sum of the phase current values is larger than or equal to the second threshold; and it is determined that a through-current has occurred in the transistors when both a condition that at least one of the absolute values of the phase current values is larger than or equal to the first threshold and a condition that the absolute value of the sum of the phase current values is larger than or equal to the second threshold are satisfied.