To provide a radio communication system which eliminates the necessity to mount a battery to the small apparatus such as a radio tag, easily selects one of the multiple apparatuses, and starts radio communication with the selected apparatus.

A radio wave signal is transmitted from a question machine 1 so as to bring a plurality of radio tags 2 into operation states. In this state, the light emission part 21 of the question machine 1 is made to emit light. The light beam of the light emission part 21 is made incident to the light receiving part 37 of one radio tag 2, thereby allowing only the radio tag 2 to perform a response. Consequently, one of the plurality of radio tags 2 is easily selected and radio communication is started with the selected radio tag 2.