A radio-frequency tag communication device including a receiver array antenna device for receiving a reply signal, a cancel-signal generating portion configured to generate a cancel signal for eliminating a leakage signal that is a part of a transmitted signal, which part is received by the receiver array antenna device, a cancel-signal control portion configured to control a phase and/or an amplitude of the cancel signal generated by the cancel-signal generating portion, and a received-signal combining portion configured to combine together received signals received by a plurality of antenna elements of the receiver array antenna device, to obtain a composite signal, and wherein the transmission of the transmitted signal and the reception of the received signals are concurrently controlled, and the cancel signal generated by the cancel-signal generating portion is applied to the received-signal combining portion, whereby the received signals and the cancel signal are combined together, so that a signal/noise ratio of a wave detector output upon demodulation of the composite signal is improved to increase the maximum distance of communication.