A communication terminal device includes a UHF-band RFID system including a wireless IC element for UHF-band RFID and a loop-shaped conductor coupled to the wireless IC element for UHF-band RFID, and a UHF-band mobile communication system including a wireless IC element for UHF-band mobile communication and an antenna conductor coupled to the wireless IC element for UHF-band mobile communication. The loop-shaped conductor and the antenna conductor are closely adjacent to each other. The loop-shaped conductor is electromagnetically coupled to a portion of the antenna conductor.