To provide a distribution control system which is adaptive to performance differences of optical modules, wiring lengths of optical cables, an increase or decrease of field devices, etc., by making corrections corresponding to an amount of variation in distortion width of a reception waveform.

The distribution control system is equipped with a host field device exchanging communication information with a plurality of field devices exchanging communication information on measurement and control of a controlled system, and a transmission line of an optical cable transmitting the communication information via the plurality of field devices so that the communication information circulates in one direction, each of the plurality of field devices having a control circuit of an optical communication interface sending and receiving the communication information to and from the transmission line. The optical communication interface control circuit has a waveform distortion detecting circuit which detects a waveform distortion width included in the received communication information and a waveform distortion correcting circuit which corrects the communication information to be sent out matching the waveform distortion width detected by the waveform distortion detecting circuit.