According to the present invention, the apparatus receives a radio frequency (RF) signal transmitted from the Radio Frequency Identification (RFID) reader, measures the strength of the received RF signal, and controls the power supplied from the power supply unit included in the tag or the power excited by the RF signal to be supplied to the tag according to whether the power excited by the received RF signal exceeds a level necessary to operate the tag based on the measured strength of the RF signal. Thus, efficiency of power consumption of the tag and the RFID transmission/reception system can be maximized and the amount of data is reduced to the extent that the set of commands is not needed, thereby simplifying a data process.