A system and method for preventing hacking of blockchain is proposed. The system includes a cryptocurrency owner configured to own a cryptocurrency wallet storing a cryptocurrency, a public key, and a private key, and capable of setting monitoring-subjected data and monitoring-excluded data, a hacking countermeasure system configured to check status of the cryptocurrency wallet by being connected to the cryptocurrency owner to receive the cryptocurrency and the public key, invalidate a hacking transaction when the hacking transaction matching the monitoring-subjected data is received, and allow the cryptocurrency to be traded by opening the cryptocurrency wallet with the private key and process transaction details into a block file when a monitoring-excluded transaction matching the monitoring-excluded data is received, and a blockchain network configured to receive the block file from the hacking countermeasure system and duplicate the block file into a plurality of block files to distribute and store each block file.