An IP server sends e-mail to a mobile device MS. This e-mail includes an application specifier that specifies startup of a Java application stored in mobile device MS and a data specifier that includes data used in operations executed by mobile device MS in accordance with a Java application. On the other hand, the ADF for the Java application stored in mobile device MS includes trusted source data containing a plurality of e-mail addresses that indicate trusted origins. Mobile device MS compares the e-mail transmission origin address with the trusted source data. Mobile device MS, only in the case where the transmission origin address of the received e-mail is included in the trusted source data, starts up a Java application based on an application specifier included in said e-mail, and uses data included in said data specifier in operations executed by that Java application.