The context information management system enables the management of context information while maintaining the security of user information. It includes a user domain management server that manages a list of domains in which users have an account, and a one-time account management server that manages temporarily issued one-time accounts for a user's account. For an account information notifying request from a client, it notifies an account group ID corresponding to the user ID, and a one-time account issued for the account group ID to the client, thereby enabling the management of the user's account and context information while hiding the user ID.