As an example of embodiments, there is disclosed a peripheral device control method of realizing a function designated by the user by controlling a peripheral device. The method has an installation function information obtaining step of obtaining installation function information showing what functions have been installed or what functions are not installed among functions which are realized by communicating with the peripheral device, a display control step of controlling a process to display the installed functions or/and the functions which are not installed so that they can be discriminated by using the installation function information obtained in the installation function information obtaining step, a receiving step of receiving an instruction of addition, updating, or deletion of the functions displayed by the displaying process which is controlled in the display control step, and a function managing step of executing at least one of a process to add and validate the function received in the receiving step, a process to delete and invalidate the designated function, and a process to update the function as an updating target to another designated function and validate such another designated function in accordance with the instruction received in the receiving step.