A portable telephone system comprising first portable telephone terminal, second portable telephone terminal and a server for performing a management of position information of the first portable telephone terminal. The server is a relay server for position search service and registers into a password managing data base a password for allowing the second portable telephone terminal to search the position of the first portable telephone terminal in advance. The first portable telephone terminal notifies the password registered in the password managing data base to the second portable telephone terminal with a mail or the like. The second portable telephone terminal achieving the password transmits a position search request message to the server. The server checks the password indicated by the search request message, allows the position search and issues a search instructing message to the first portable telephone terminal.