When an RFID-tag is formed by joining a semiconductor chip (RFID chip) to an antenna consisting of a rolled metal foil or the like using ultrasonic waves, the pressure impressed to the semiconductor chip is suppressed to avoid the damage of the semiconductor chip. For this purpose, the present invention provides an RFID-tag 1 wherein gold bumps are joined to the metal foil by pressing the gold bumps formed on the semiconductor chip against an antenna member, and impressing ultrasonic waves; and the RFID-tag wherein a matte surface having a low glossiness is formed on the metal foil, or a surface having shallow rolling streaks is formed on the metal foil, and gold bumps are joined to the surface.