A temperature input unit includes a disconnection detection circuit that measures a temperature of a measurement target with at least one of a thermocouple or a temperature measurement resistor and feeds a disconnection detection current for disconnection detection to the thermocouple and a compensating wire connected to the thermocouple. A controller controls, before measuring the temperature of the measurement target with the thermocouple, a terminal switch and an input circuit switch to connect the compensating wire to a temperature measurement resistor input circuit and an A/D converter, and calculates a predicted value of a voltage drop resulting from resistance of the compensating wire occurring in response to the disconnection detection current. The controller controls the terminal switch and the input circuit switch to connect the compensating wire to a thermocouple input circuit and the A/D converter, and subtracts the predicted value from a measured value of the thermoelectromotive force detected by the thermocouple input circuit to calculate a corrected measured value of the thermoelectromotive force.