In order to prevent reduction in performance due to variations in illuminance of external light, a liquid crystal display unit includes: a pixel section including pixels arranged at each of intersections where a plurality of scanning lines and a plurality of signal lines intersect, and optical sensor circuits provided to at least part of the pixels; an imaging section which generates a multi-gradation image based on detection results of the optical sensor circuits; and a gradient value calculation section which calculates a gradient value which is a ratio of a variation in a gradation tendency value of the multi-gradation image to a variation in sensitivity of the optical sensor circuits.