POWER SUPPLY CONTROL APPARATUS

A heater drive apparatus functions as a power supply control apparatus, and controls power supply to an electrical heating wire. In the heater drive apparatus, a current output circuit and a detection resistor function as a current detection unit, and detect a current flowing through the electrical heating wire. A microcomputer repeatedly calculates an electrical heating wire temperature relating to the electrical heating wire based on the detected current. A drive circuit functions as a switching unit, and switches a switch on or off in accordance with the calculated electrical heating wire temperature.