A sensor voltage reading circuit for reading an analog sensor value is provided which can remove electromagnetic wave noise inputted to an input terminal of an A/D conversion circuit. The sensor voltage reading circuit includes a first voltage division circuit and a second voltage division circuit for dividing the output voltage of a potentiometer. An A/D conversion circuit has input terminals connected to the output terminals of the voltage division circuits and a processing unit for reading digital voltages obtained by conversion of the A/D conversion circuit. The processing unit removes from the converted voltages a noise voltage caused by radio waves which mix into the input terminals of the A/D conversion circuit. Accordingly, the reading accuracy of the output voltage of the sensor can be enhanced. In a further embodiment, the sensor voltage reading circuit can suppress power dissipation by the analog sensor to achieve miniaturization of the power source circuit.