Provided are an antenna using an inductively coupled feeding method, a Radio Frequency Identification (RFID) tag thereof, and an antenna impedance matching method thereof. The antenna includes a resonator for determining a resonance frequency of the antenna and a feeder for providing an RF signal to an element connected to the antenna. An RFID tag includes an antenna which receives an RF signal from the RFID reader, an RF front-end which rectifies and detects the RF signal, and a signal processor which is connected to the RF front-end. Particularly, the antenna includes a resonator for determining a resonance frequency of an antenna and a feeder for providing the RF signal to the RF front-end, wherein mutual inductive coupling between the resonator and the feeder is performed.