A settlement system with higher security which replaces a settlement system using credit cards is provided. The settlement system has a user terminal, a settlement device, and a settlement terminal. First, a user ID, a password, and amount information identifying an amount are inputted in the settlement system (S912), and sent to the settlement device (S913). The settlement device performs credit determination (S922), generates temporary permission information if credit is possible (S923), and sends the temporary permission information to the user terminal (S924). The user terminal generates a one-time password (S915). The one-time password is inputted to the settlement terminal (S931). If the one-time password sent from the settlement terminal to the settlement device is identical to the one-time password created in the settlement device (S926), the settlement device allows a user's payment (S927).