A transmission/reception antenna and a transmission/reception device using the antenna wherein the antenna includes a dielectric base board, an excitation loop antenna provided on the dielectric base board, a transmission/reception loop antenna provided on the dielectric base board in close proximity of but not in contact with the excitation loop antenna, and a resonance capacitor connected between two ends of the transmission/reception loop antenna. A coupling capacitor is connected to one of the two ends of the transmission/reception loop antenna. The excitation loop antenna is connected to a transmitter, and the transmission/reception loop antenna is connected to the receptor via the coupling capacitor. Thereby, the frequency property may be expanded without increasing the power consumption, and the reception processing unit is enabled to properly process the reception signal.