An image forming apparatus receives, from a server connected to a network, a notification that a module operating units composing the apparatus can be added. The apparatus requests distribution of a program including the module to the server. Further, when a function of the module can be realized from information of the module stored in each hierarchy composing the program of the apparatus acquired each predetermined period and information of main and option devices, the server transmits program distributing information including the module. The device stores the module in an area of a predetermined hierarchy on the basis of the program distributing information.