PURPOSE: To simplify the management of parts by reducing the number of parts and to improve productivity by simplifying the process of manufacture for liquid crystal display device.

CONSTITUTION: On the respective counter faces of a pair of glass boards 5 and 6, a pair of mutually crossing transparent electrodes 7 and 10 and oriented films 9 and 11 to cover these transparent electrodes 7 and 10 are formed, between the respective oriented films 9 and 11, a liquid crystal cell 1 enclosed a liquid crystal material 13 and a polarizer 2 on the light incident side of this liquid crystal cell 1 are provided and on the light emitting side, a photodetector 4 is provided respectively. At such a liquid crystal display device, a torsional phase plate 20 is provided through an oriented film 21 on the lower face of the up side glass board 6 of the liquid crystal cell 1 so that this torsional phase plate 20 can be integrated with the liquid crystal cell 1.