A transmission/reception device, comprising: a transmission/reception antenna, a transmission processing unit (10; 48) for forwarding a transmission signal to the transmission/reception antenna; a reception processing unit (9; 49) for receiving a reception signal from the transmission/reception antenna; and a control unit (8; 50) for controlling the transmission processing unit and the reception processing unit; wherein the transmission/reception antenna comprises: a magnetic member (11; 51); an excitation loop antenna (12; 52) disposed on the magnetic member; a transmission/reception loop antenna (14; 53) disposed on the magnetic member adjacent to but not in contact with the excitation loop antenna; and a resonance capacitor (15; 54) connected between two ends of the transmission/reception loop antenna; wherein the excitation loop antenna is a loop of a single turn, and the transmission/reception loop antenna comprises a loop of a plurality of turns, the excitation loop antenna and the transmission/reception loop antenna being coaxially wound around the magnetic member; the transmission/reception loop antenna comprises a first loop of a plurality of turns and a second loop of a plurality of turns and a connecting portion connecting one end of the first loop to one end of the second loop, the first and second loops of the transmission/reception loop antenna being located on either side of the excitation loop antenna symmetric to each other; the transmission/reception antenna further comprises: a pair of transmission processing unit connecting terminals connected to the excitation loop antenna and connected to the transmission processing unit; and a pair of reception processing unit connecting terminals connected to opposite ends of the first and second loops to the one ends thereof and connected to the reception processing unit; the resonance capacitor being connected between the opposite ends of the first and second loops of the transmission/reception loop antenna, wherein a signal forwarded by the transmission processing unit to the excitation loop antenna is transmitted to the transmission/reception loop antenna and then transmitted. a transmission/reception antenna, a transmission processing unit (10; 48) for forwarding a transmission signal to the transmission/reception antenna; a reception processing unit (9; 49) for receiving a reception signal from the transmission/reception antenna; and a control unit (8; 50) for controlling the transmission processing unit and the reception processing unit; wherein the transmission/reception antenna comprises: a magnetic member (11; 51); an excitation loop antenna (12; 52) disposed on the magnetic member; a transmission/reception loop antenna (14; 53) disposed on the magnetic member adjacent to but not in contact with the excitation loop antenna; and a resonance capacitor (15; 54) connected between two ends of the transmission/reception loop antenna; wherein the excitation loop antenna is a loop of a single turn, and the transmission/reception loop antenna comprises a loop of a plurality of turns, the excitation loop antenna and the transmission/reception loop antenna being coaxially wound around the magnetic member; the transmission/reception loop antenna comprises a first loop of a plurality of turns and a second loop of a plurality of turns and a connecting portion connecting one end of the first loop to one end of the second loop, the first and second loops of the transmission/reception loop antenna being located on either side of the excitation loop antenna symmetric to each other; the transmission/reception antenna further comprises: a magnetic member (11; 51); an excitation loop antenna (12; 52) disposed on the magnetic member; a transmission/reception loop antenna (14; 53) disposed on the magnetic member adjacent to but not in contact with the excitation loop antenna; and a resonance capacitor (15; 54) connected between two ends of the transmission/reception loop antenna; wherein the excitation loop antenna is a loop of a single turn, and the transmission/reception loop antenna comprises a loop of a plurality of turns, the excitation loop antenna and the transmission/reception loop antenna being coaxially wound around the magnetic member; the transmission/reception loop antenna comprises a first loop of a plurality of turns and a second loop of a plurality of turns and a connecting portion connecting one end of the first loop to one end of the second loop, the first and second loops of the transmission/reception loop antenna being located on either side of the excitation loop antenna symmetric to each other; the transmission/reception antenna further comprises: a pair of transmission processing unit connecting terminals connected to the excitation loop antenna and connected to the transmission processing unit; and a pair of reception processing unit connecting terminals connected to opposite ends of the first and second loops to the one ends thereof and connected to the reception processing unit; the resonance capacitor being connected between the opposite ends of the first and second loops of the transmission/reception loop antenna, wherein a signal forwarded by the transmission processing unit to the excitation loop antenna is transmitted to the transmission/reception loop antenna and then transmitted.