PURPOSE: To obtain the multifunctional multipurpose liquid crystal arithmetic unit which utilizes liquid crystal cells.

CONSTITUTION: The liquid crystal arithmetic unit is constituted by arranging a couple of liquid crystal cells for transmitted light having a specific plane of polarization. The 1st liquid crystal cell 1 is equipped with electrode means 8 and 9 which impress voltages corresponding to 1st data and a liquid crystal layer 7 which rotates the plane of polarization corresponding to the impressed voltages. The 2nd liquid crystal cell 2 is equipped with electrode means 13 and 14 which impress voltages corresponding to 2nd data and a liquid crystal layer 12 which further rotates the plane of polarization according to the impressed voltages. The 1st and 2nd data can optically be added according to the addition of the angle of rotation of the plane of polarization.