To easily enter arbitrary telephone directory information in a telephone directory DB of a telephone device from a radio telephone terminal via a communication network.

In the telephone device 10, a storage section stores a mail address of an authorized registrant who can register the telephone directory information in the telephone directory DB as registrant information, it is checked whether the sender is an authorized registrant based on whether the sender address of the electronic mail received via the communication network 50 from a radio telephone terminal 20 has been registered in the registrant information. After checking that the sender is an authorized registrant, the telephone number and information on one's party are extracted from the electronic mail and are registered in a telephone directory DB14C.