A block consensus method of a computing device is provided. The computing device receives a delegate request message including transaction hashes from each of a plurality of nodes, generates a prepared block including transaction hashes based on the delegate request message, and transmits a prepare message including the prepared block to the nodes. The computing device receives a commit message including a proof of consensus on a validity of the prepared block from the nodes, and transmits a reply message including a final block decided based on the commit message.