A simple authentication method using browser web storage according to an embodiment of the present disclosure includes the operations in which: on the basis of a received user key, a server generates an authentication token, a public key and a private key, stores the same in a session, and transmits the authentication token, the public key and a session key corresponding to the session to a terminal; by using the received public key, the terminal encrypts PIN number data entered by a user, and transmits the encrypted data along with the received session key to the server; and by using the private key corresponding to the received session key, the server decrypts the PIN number data to perform simple authentication, wherein the user key and the PIN number data may be stored in the terminal web storage and set differently for each device or browser.