Display device

A display device comprising an optical sensor in a pixel region on an active matrix substrate, wherein the optical sensor includes:

• a photodetecting element for receiving incident light;
• a reset signal line for supplying a reset signal to the optical sensor;
• a readout signal line for supplying a readout signal to the optical sensor;
• an accumulation node having a potential that varies with an amount of light received by the photodetecting element during a sensing period, the sensing period being a period from supply of the reset signal to supply of the readout signal;
• an amplifying element for amplifying the potential of the accumulation node according to the readout signal;
• and
• a sensor switching element for reading out the potential amplified by the amplifying element and outputting the potential as a sensor circuit output to an output line,
• wherein a light shielding film is provided on a side opposite to a light receiving surface side with respect to the photodetecting element,
• the light shielding film is connected to a power source for supplying a voltage for fixing a potential of the light shielding film to a constant potential, and
• the following formula is satisfied:
• VLS≧VRST.H
• where VLS represents the constant potential and VRST.H represents a high level potential of the reset signal.