Mobile unit 16 which can activate Java-AP software receives SDF (Security Descriptive File) 204 from administering server unit 18 which a trustworthy organization (a communication provider which administers mobile packet communication network 15) administers, and obtains ADF 205 from IP server unit 13 by using URL contained in the SDF, and obtains Jar file 206 from IP server unit 13 by using ADF 205, and installs in itself Java-AP containing these files. Java-AP, which is achieved by activating the installed Java-AP software, operates within the range of authorization expressed by policy information contained in SDF 204.