A wireless tag readerwriter device of one example of the present invention sends question signals to a plurality of wireless tags at once and receives response signals sent from the wireless tags. In a first embodiment, jacketed, insulated wire is used as one winding of a toroidal transformer, while unjacketed insulated wire is used as another winding. Manual operation of the extension triggers and retraction trigger allows extension or retraction of the in line rollers as required. An error corrector samples demodulation data in response to the demodulation data strobe signal and reproduces the data to the original digital data. Further, the plane where the hollow structure is formed has a dense structure.