A fixing apparatus includes a transformer, a heater, a temperature acquiring portion, and control portion. A first switching unit allows or cuts off power supply from a primary-side circuit to the heater by supplying power, and a second switching unit allows or cuts off power supply from the primary-side circuit to the temperature acquiring portion by supplying power. The power supply to the heater can be allowed or cut off according to the temperature of the heater acquired by the temperature acquiring portion. In addition, the control portion cuts off power supply from the primary-side circuit to the heater and power supply from the primary-side circuit to the temperature acquiring portion by controlling operations of the first switching unit and the second switching unit with the one signal.