Power supply apparatus capable of detecting abnormality in current flowing in drive circuit

A current detection unit (60a) samples motor current (MCRT) at every cycle corresponding to a cycle of the highest processing speed of a CPU. A current integral calculation unit (62) integrates the value of the sampled motor current (MCRT) over a sampling period to calculate and output a current integral (Is) to an abnormality determination unit (64a). The abnormality determination unit (64a) determines whether the current integral (Is) is larger than a threshold (Is_std). When the abnormality determination unit determines that the current integral (Is) is larger than the threshold (Is_std), it generates a detection signal (DET) indicating an abnormality in the motor current (MCRT) and outputs the signal to a relay drive unit (66) and a notification unit (68). The relay drive unit (66) receives the detection signal (DET) to generate a signal (SE) for turning off a system relay. The notification unit (68) receives the detection signal (DET) to generate and output a signal (AL) to display means provided outside a power supply apparatus.