An NFC (near field communication) device can include a resonance unit and an NFC chip. The resonance unit may communicate with an external device through an electromagnetic wave. The NFC chip can provide output data to the resonance unit, receive input data from the resonance unit, and can reduce a Q factor (quality factor) of the resonance unit when a signal receive operation is performed in a card mode, and can maintain the Q factor of the resonance unit in a reader mode and when a signal transmit operation is performed in the card mode.