1 : A mobile communication device comprising an environment as a mobile communication device platform and an application execution environment configured on the mobile communication device platform, wherein: the application execution environment has a function of providing a first software interface, for receiving an instruction regarding a wallpaper setting to be given to a wallpaper setting program operating, as a default application on the mobile communication device platform, for a user setting application operating on the application execution environment; the mobile communication device platform has a function of providing a second software interface for receiving the instruction regarding the wallpaper setting, for the application execution environment; the application execution environment passes a request corresponding to the instruction regarding the wall paper setting to the mobile communication device platform through the second software interface when the application execution environment receives the instruction regarding the wall paper setting through the first software interface; and the mobile communication device platform makes a wall paper setting in accordance with the request received from the application execution environment.