The blockchain technique was first proposed by Satoshi Nakamoto in 2008. It is used for a distributed database technology. Public Key Infrastructure(PKI) system, which is one of the key management systems, is a centralized system. There is a possibility of a single point of failure in the currently used centralized PKI system. Classical digital signature algorithm; ECDSA has used the well-known cryptocurrencies, such as Bitcoin and Ethereum. Using the Shor's algorithm, ECDSA can be broken by the quantum computing attack. In this thesis, we propose a blockchain-based key management system using quantum-resistant cryptography, since we use a GLP digital signature scheme, which is a lattice-based mathematical problem. It is secure against the quantum adversary and ensures long-term safety. Besides, we design a decentralized blockchain structure, and it is secure for the single point of failure.