1. An information processing device for installing and executing an application program which enables at least one of a plurality of information processing functions provided with said information processing device, comprising: a storage part for storing functional restriction information for each of a plurality of users which shows a functional restriction for each user on use of said plurality of information processing functions, said storage part including a shared storage region commonly available for the plurality of users, and a user storage region assigned for each of the plurality of users individually; an obtaining part for obtaining, based on said functional restriction information for each user, common functional restriction information which shows that said plurality of information processing functions are unavailable except for a function commonly available for all of the plurality of users; a determination part, in installation of said application program, for determining whether or not a command contained in said application program enables an unavailable function shown by said common functional restriction information by analyzing the command; a rewrite part for rewriting the command contained in said application program to disable said unavailable function shown by said common functional restriction information when the command is determined to enable said unavailable function; an installation part for installing said application program containing the command rewritten by said rewrite part; said shared storage region stores a library in which execution of a functional process to effectively enable at least one of said plurality of information processing functions is defined and a dummy library in which execution of a dummy process executed to replace said functional process without enabling at least one of said plurality of information processing functions is defined, and said rewrite part rewrites the command to execute said library contained in said application program to be installed as the command to execute said dummy library, thereby rewriting the command to disable said unavailable function restricted with said common functional restriction information when the command enabling said unavailable function restricted with said common functional restriction information is contained in said application program.