Each pixel includes first and second photodiodes that are receiving-light detecting elements. The first photodiode applies a first potential according to an amount of light entering into the corresponding pixel. An internal node is electrically coupled with an internal node in another pixel via a resistance component. Hence, the second photodiode applies a second potential according to an average amount of light on the periphery to the corresponding internal node. A pixel signal generating circuit reads out a multiplied result of the first and second potentials as a pixel signal. The pixel signal has an intensity corresponding to the amount of light in the pixel in accordance with a receiving-light sensitivity characteristic (signal amplification factor) that is automatically adjusted based on an average amount of light in a region on the periphery of the pixel.