A method for authentication based on a blockchain network is provided. The method includes steps of: an authentication-supporting server (a) if verification is requested by a certificate authority (CA) app, verifying a signature value and transmitting an access token to a user device, supporting the CA-affiliate app to transmit a login request to a CA-affiliate server, and registering the access token in the blockchain network, and transmitting a verification request to the blockchain network to transmit the access token to the authentication-supporting server, and register the access token in the blockchain network, and transmitting the access token to the user device, and transmit the login request to the CA-affiliate server, and (b) performing one of (i) verifying the access token, and (ii) transmitting the verification request to the blockchain network, and transmitting a verification-result to the CA-affiliate server, to allow the CA-affiliate app to log in to the CA-affiliate server.