An RF tag is disclosed that includes an antenna and an integrated circuit connected to the antenna. The antenna includes a first radiating element, a second radiating element, a feeding part connected in series between the first and second radiating elements, and an impedance control part connected parallel to the feeding part. An auxiliary radiating element connected to one or both of the first and second radiating elements is used for radio communication with the integrated circuit before completion of the RF tag, and is not used for radio communication after the completion of the RF tag.