By using a unique ID generated by considering the hardware characteristic of PC in PDA where an application program, etc. distributed based on PC is installed, it makes possible to generate and authenticate a virtual unique ID in PDA so as to authenticate drive of the application in PDA. As such, the file size of a distributed edition is small in its characteristic and it is difficult to have a protecting means such as security, etc. in view of the characteristic of device. Hence, illegal distribution is easy and a more certain solution is provided so as to prevent illegal copy of the application in PDA having a feasible characteristic in protecting copyright.