An image processing apparatus which can be readily used by an authenticated user without laborsome setting even if the user uses the image processing apparatus for the first time through an authentication server. A user is authenticated with an authentication server connected to an image processing apparatus via a network. User unique setting information for the authenticated user is set, and the user unique setting information for each user is stored in user information storing areas. Initial setting information of initial setting of the image processing apparatus is stored in an initial setting information storing area. When the authenticated user uses the image processing apparatus for the first time, duplicate copy of the initial setting information stored in the initial setting information storing area is stored as the user unique setting information in the user information storing areas.