Synchronization control system

According to an embodiment, the transmission processor of the master terminal includes a sending/receiving processor which sends a synchronization request demanding packet to a particular slave terminal and sends a synchronization reply packet when receiving a synchronization request packet from the slave terminal that has received the synchronization request demanding packet, and a synchronization controller which calculates a synchronization band from the time of the receipt of the data packet and from time information added to the received data packet to determine a synchronization state and which adjusts a correction amount in accordance with the synchronization state and sends an internal timing correction command to the timing generator.