A light receiving device is disclosed by which a reception characteristic of a light receiving system can be improved. The light receiving device includes a photoelectric conversion element for receiving a light signal and performing photoelectric conversion of the light signal, and a data detection section for using an decision level for the light signal received by the photoelectric conversion element to detect modulation data included in the light signal. The light received device further includes an decision level control section for feedforward controlling the decision level to be used by the data detection section based on a level of the received light signal.