A power supply circuit of an aircraft includes: a first power transmission path for transmitting electric power from each of a first main power source device and a second main power source device to a first load device and a second load device; a first current sensor; a second current sensor; a third current sensor; and a fourth current sensor, and determines whether an abnormality has occurred based on currents detected by the first current sensor, the second current sensor, the third current sensor and the fourth current sensor.