Abstract: Method and system for providing an integrated user management environment to multi-Internet service, the method including the steps of (1) making a user's client system to login a member management domain provided in a web service of a main server system for using a particular internet service, (2) providing a required single user ID information to the member management domain, (3) making the member management domain to authenticate the provided user ID information, (4) transferring specific information on the authenticated user from the member management domain to the user's client system, and (5) making the user's client system to login a service domain provided from a service server system by using the specific information, whereby providing the user with one of multi-Internet service in a portal service by using the single ID information only, whereby permitting the user to login multi-Internet service by using only one ID under the same user environment, and to use other services only by one time authent