The present invention is to provide an optical feedback control unit for determining an optical output by a feedback control, an optical communication system, a feedback control method, and a recording medium for recording a program. According to the present invention, even when used in the system to which a plurality of nodes are connected, the unstable system may become stable by the proper feedback control without being affected by the optical level change according to the polarized variation or the loss variation. In The optical feedback control unit according to the present invention, an optical output control portion determines an optical output by a feedback control using the result detected by a detection portion, a dead zone not performing the feedback control is set for the difference between the detected value from the detection portion and the control target value, and when the difference between the detected value and the control target value is within the dead zone, a width of the dead zone is set to be wider than that of the dead zone when the difference between the detected value and the control target value is out of the dead zone.