Abstract: Provided is a photo sensor that can be downsized while suppressing occurrence of noise caused by a dark current, and a display device including the photo sensor. The photo sensor used includes a plurality of photodiodes (9-11) formed in a same silicon layer (8). The photodiodes (9-11) have p-type semiconductor regions (9a, 10a, 11a) and n-type semiconductor regions (9c, 10c, 11c) formed respectively in the silicon layer (8). Further, the photodiodes (9-11) are arranged in series so that the respective forward directions will be aligned with each other. In two photodiodes adjacent to each other, the n-type semiconductor region of one of the photodiodes and the p-type semiconductor region of the other photodiode are formed to overlap each other in the thickness direction of the silicon layer.

Abstract: A first shield electrode (516), which is an electrostatic shield, is formed so as to be closer to a glass substrate (314) side than wiring (265) is. A power source circuit (266) supplies, to the first shield electrode (516), a reference potential (Vr?nVoc) equal to that of a cathode of a PIN photodiode (413). Thus, inductive noise for wiring for transmitting an output from a photoelectric conversion device used for an ambient light sensor is further reduced in a display device.