An image forming apparatus of the present invention includes a circuit including both a circuit within a fixing unit and a power control circuit, provided with a first circuit which supplies power to a heater from an AC power supply, a second circuit electrically insulated from the first circuit, and a third circuit electrically insulated from both the first circuit and the second circuit, all of the first to third circuits are provided on at least one surface of a circuit board, and the first to third circuits are disposed on at least one straight line on which all of the first to third circuits are present on the one surface of the circuit board in the order of the first circuit, the third circuit and the second circuit.