A light valve device includes a driving substrate having a shading zone and a photic zone. A shading unit includes a first shading plate, two driving devices, and second shading plates respectively connected to the two driving devices. The driving devices and the first shading plate are fixed in the shading zone adjacent to the driving substrate. The first shading plate is between the two driving devices. The driving devices are operable to drive the two second shading plates close to the first shading plate to make the second shading plates face the photic zone of the driving substrate for preventing light entering the driving substrate. By locating the light valve device under the sub pixel, the dynamic contrast can be raised to promote the display effect.