An image processing apparatus restricts the use of functions on a user-by-user basis as well as easily suppresses the realization of a function that is equivalent to a restricted function by combining other functions. To accomplish this, an image processing system includes an image processing apparatus and an information processing apparatus that includes function restriction information for restricting, on a user-by-user basis, the use of functions provided by an image processing apparatus. Furthermore, the image processing apparatus acquires function restriction information corresponding to an authorized user, and if a function whose use is restricted by function restriction information can be realized by combining other functions, the image processing apparatus restricts the use of the other functions.