An automatic light measuring device for an image pickup device includes a pair of line sensors suitable for an automatic focusing adjustment and disposed on a semiconductor chip at positions spaced apart by a predetermined distances, an integration time controller for generating an integration control signal for controlling the charge accumulation by incident light by detecting the amount of charges accumulated in the line sensors, a first exposure amount detector for calculating the intensity of incident light from the integration control signal, a second exposure amount detector inclusive of photoelectric conversion elements formed on the semiconductor chip, for detecting the amount of incident light, a pair of lenses mounted above the pair of line sensors for focusing the image of substantially the same subject within the central area of the field of view, and an optical system for applying light within the area broader than the central area of the field of view to the surface of the semiconductor chip inclusive of the photoelectric conversion elements. The photoelectric conversion elements are disposed between the pair of line sensors. The optical system may be made of an acrylic rod, light focusing fibers, retrofocus lens, or the like.