A user terminal displays on its display unit a target web page including an authentication information input field into which input authentication information is inputted by the user terminal. The user terminal judges first to third validity levels for a plurality of login history information by referring to a login information list and a service group information. The user terminal selects a corresponding process from a plurality of predetermined processes for the input authentication information based on existence or absence of the login history information in the first or second validity level and on a result of checking the input authentication information with login information in the login history information in the first to third validity levels. The user terminal executes the corresponding process.