An RFID tag includes a circuit board, an RFID IC and a functional module. The circuit board has an antenna conductor. The RFID IC is mounted on the circuit board. The functional module is connected to the circuit board through a lead wire. An electrical length of a connection wiring that electrically connects the functional module to an element on the circuit board is within ±10% of an integral multiple of a half wavelength of a radio signal that the RFID IC transmits or receives.