One aspect of the present invention is to provide a login system and method which can be easily applied to corporate members, and which can prevent unauthorized use even if authentication information is copied. Because of a configuration in which login is carried out by using service right data for each medium identifier of a secure storage medium, unless a dishonest person uses the secure storage medium, it is impossible to log in even if the dishonest person copies authentication information. Further, provided that the secure storage medium is distributed to every signal person belonging to a corporate body, it can be applied to corporate users in the same way as individual users.