A circuit fault detection apparatus includes an AD conversion circuit, a corrector, first and second determination devices, and a fault detector. The AD conversion circuit detects a voltage corresponding to a current or a voltage applied to the circuit fault detection element, and converts the voltage to a digital value. The corrector corrects a measurement value to a corrected measurement value. The first determination device determines whether or not the electric circuit has the fault, based on a comparison between an uncorrected measurement value and an uncorrected threshold value. The second determination device determines whether the electric circuit has the fault, based on a comparison between the corrected measurement value and a corrected threshold value. The fault detector detects the fault in the electric circuit, based on a condition that at least one of the first or second determination devices determines that the electric circuit has the fault.