A method for synchronizations with delayed data serving as backup data stored in one or more delayed nodes in a blockchain network, to thereby restore one or more service nodes in the blockchain network while maintaining a reliability of the backup data is provided. The method includes steps of: (a) a specific delayed node among the delayed nodes performing synchronization with the services nodes while the specific delayed node maintains a specific delay according to a specific initial setting thereof; (b) the specific delayed node, when a triggering command is acquired from an administrating device, transmitting information on delayed blocks included therein to the service nodes in order to support restoration of the service nodes; and (c) the specific delayed node, after the service nodes are restored by using the information on the delayed blocks, performing the synchronization again with the service nodes.