A temperature control apparatus includes a resistance heater whose a resistance value changes depending on a temperature of the resistance heater; a signal generator to output a control signal having two voltage levels including a first-voltage and a second-voltage; a switching section to flow a first current through the resistance heater when the voltage level of the control signal is the first-voltage, and to flow a second current having a current value smaller than that of the first current through the resistance heater when the voltage level of the control signal is the second-voltage; and a voltage measuring instrument to measure a voltage value across the resistance heater at the time when the second current flows through the resistance heater. The signal generator controls the temperature of the resistance heater based on the voltage value measured by the voltage measuring instrument.