A digital protection control system comprising as a terminal station: a reference station configured to take system current information and function as a reference of sampling time; at least one tail-end station configured to take system current information from a power system; and at least one intermediate station configured to be connected through a transmission path between the reference station and the tail-end station, wherein: the digital protection control system is configured to transmit and receive system current information among a plurality of the terminal stations (4, 6, 7) including the reference station, the intermediate station and the tail end station and to perform protection control of the power system, characterized in that the terminal stations (4, 6, 7) being configured to be operable under a sampling synchronization in a tree form; and in that the intermediate station includes an upper transmission unit connected to a transmission path of the reference station side and a plurality of lower transmission units (7-15; 7-16; 7-17) connected to a transmission path of the tail-end station side, and is configured to subordinate time of the intermediate station to time as a reference of a terminal station connected to the upper transmission unit, and subordinates time of a terminal station connected to the lower transmission units (7-15; 7-16; 7-17) to time as a reference of the intermediate station. a reference station configured to take system current information and function as a reference of sampling time; at least one tail-end station configured to take system current information from a power system; and at least one intermediate station configured to be connected through a transmission path between the reference station and the tail-end station, wherein: the digital protection control system is configured to transmit and receive system current information among a plurality of the terminal stations (4, 6, 7) including the reference station, the intermediate station and the tail end station and to perform protection control of the power system, characterized in that the terminal stations (4, 6, 7) being configured to be operable under a sampling synchronization in a tree form; and in that the intermediate station includes an upper transmission unit connected to a transmission path of the reference station side and a plurality of lower transmission units (7-15; 7-16; 7-17) connected to a transmission path of the tail-end station side, and is configured to subordinate time of the intermediate station to time as a reference of a terminal station connected to the upper transmission unit, and subordinates time of a terminal station connected to the lower transmission units (7-15; 7-16; 7-17) to time as a reference of the intermediate station. the digital protection control system is configured to transmit and receive system current information among a plurality of the terminal stations (4, 6, 7) including the reference station, the intermediate station and the tail end station and to perform protection control of the power system, characterized in that the terminal stations (4, 6, 7) being configured to be operable under a sampling synchronization in a tree form; and in that the intermediate station includes an upper transmission unit connected to a transmission path of the reference station side and a plurality of lower transmission units (7-15; 7-16; 7-17) connected to a transmission path of the tail-end station side, and is configured to subordinate time of the intermediate station to time as a reference of a terminal station connected to the upper transmission unit, and subordinates time of a terminal station connected to the lower transmission units (7-15; 7-16; 7-17) to time as a reference of the intermediate station.