A radio communication apparatus includes a carriage path through which a radio communication medium is carried, a communication antenna provided in the carriage path, and a detector provided on an upstream side of the antenna in a carrying direction of the moving radio communication medium. The detector detects the passing radio communication medium. A radio main unit detects the radio communication medium by using the detector, and transmits a polling command to the radio communication medium at a proper timing on the basis of a detection signal from the detector. Thereby, it is possible to transmit a polling command from the radio main unit to the radio communication medium at a proper timing when the radio communication medium comes to a communication area of the antenna.