To provide a MOS differential amplifier circuit having a subtracter/ adder function, which has a good linearity over a wide input voltage range and is formed on the semiconductor integrated circuit.

A voltage subtracter/adder of this invention is so constituted that the gates of transistors M1 and M2 constitute a pair of inputs and drains constitute a pair of subtraction outputs respectively, that addition output terminals are formed by commonly connecting the sources, and that the sum of the current flowing in the transistors M1 and M2 increase in proportion to an input differential voltage.