Image forming apparatus

An image forming apparatus comprising:

• a heater including a heating element that generates heat by energization, the heater being connected to a primary-side circuit including an AC power supply;
• a driving unit that supplies electric power to the heating element, the driving unit being connected to a secondary-side circuit isolated from the primary-side circuit;
• a plurality of temperature detection portion each detecting a temperature of the heater, the plurality of temperature detection portion being connected to a potential side isolated from the primary-side circuit and the secondary-side circuit;
• a plurality of abnormality detection circuit portions that output signals corresponding to the temperatures detected by the plurality of temperature detection portion, the plurality of abnormality detection circuit portions being disposed on a potential side isolated from the primary-side circuit and the secondary-side circuit;
• and
• a relay having a coil connected to a potential side isolated from the primary-side circuit and the secondary-side circuit, the relay having a contact on a conduction path to the heater in the primary-side circuit,
• wherein the relay is disconnected according to the signals output by the abnormality detection circuit portions.