In a liquid crystal display device (1), (i) regions where respective detecting devices (201) are provided and (ii) regions where respective reference devices (202) are provided are separately arranged so as to be alternated along a frame. In each region, a predetermined number of PIN photodiodes (413) are connected in series and in parallel. In the whole of the first regions, (i) a series connection of n PIN photodiode(s) and (ii) a predetermined number of parallel connections are provided; in the whole of the second regions, (i) a series connection of n PIN photodiode(s) and (ii) a predetermined number of parallel connections are provided. Thus, even in a case where there is a great variation in the characteristics of photoelectric conversion device elements in a display panel which photoelectric conversion device elements configure a photoelectric conversion device, an intensity of ambient light can be detected accurately in the display device.