Provided is a communication control system in which a control device and one or a plurality of control target devices are connected through a network, wherein at least one of the plurality of control target devices includes a sub master and a sub slave to be synchronously controlled with each other, and the control device includes a storage unit storing each pieces of information on a synchronization period for synchronizing with the control target device, communication periods, and mutual communication control information for mutually communicate in a mutual communication period shorter than the synchronization period, a calculation unit calculating a control command for commanding an operation in synchronization with the control target device for each control target device, and a communication control unit transmitting the control command including the mutual communication control information to the sub master and the sub slave of the at least one control target device.