An RFID tag comprises a semiconductor chip storing therein information of an object to be discriminated and carrying out radio communication with a reader/writer device; and an antenna coil provided with a magnetic core member and connected electrically to the semiconductor chip. The semiconductor chip and the magnetic core member are wrapped by an insulation sheet carrying an interconnection pattern connecting a pad of the semiconductor chip and the antenna coil electrically and plural coil patterns on one side thereof. The plural coil patterns includes bar-shaped conductor patterns formed obliquely to the magnetic core member, each of the bar-shaped conductor patterns having an end connected to an end of an adjacent coil pattern, the bar-shaped conductor patterns thereby forming together a spiral coil around the magnetic core member. The coil patterns being connected with each other at a part where the coil patterns overlap with each other.