A photodetector capable of improving dynamic range for input signals is provided. This photodetector includes a photoelectric converting portion, a charge separating portion, a charge accumulating portion, a barrier electrode formed the charge separating portion and the charge accumulating portion, and a barrier-height adjusting portion electrically connected to the barrier electrode. Undesired electric charges such as generated when environment light is incident on the photoelectric converting portion are removed by the charge separating portion. A potential barrier with an appropriate height is formed under the barrier electrode by applying a voltage to the barrier electrode according to an electric charge amount supplied from the charge separating portion to the barrier-height adjusting portion. Electric charges flowing from the charge separating portion into the charge accumulating portion over the potential barrier are provided as an output of the photodetector.