To surely detect ID corresponding to a plurality of ID tags in the neighborhood of the center of a wide space.

This ID tag reading device 10 includes: an antenna system in which a plurality of loop antennas are arranged so as to be shifted on a plane, the loop antenna shaped by chaining a plurality of small loops formed by twisting a loop; an antenna driving means for driving the plurality of loop antennas by different phases, and for controlling an output power for driving; a communication means for communicating with an ID tag, and for reading information stored in an ID tag; and a control means for controlling the communication means by controlling the antenna driving means so that the output power can be gradually increased or decreased, and for repeating the reading operation of the ID tag. Thus, it is not necessary to divide a wide space by antennas, and it is possible to read the ID tag arranged in the wide reading space such as a bookshelf or a showcase.