To support a tag information reader to read information from radio communication tags, attached to each of a plurality of structural objects in a plant and to provide the locations of unread radio communication tags, a tag information acquisition unit acquires information on radio communication tags actually read by the tag information reader. Next, an unread tag extraction unit extracts radio communication tags which are a plurality of radio communication tags stored in a tag arrangement data file but from which information cannot be acquired by the tag information acquisition unit, and an unread tag arrangement calculation unit acquires arrangement data on the extracted radio communication tags. The arrangement data on those radio communication tags is sent to a display unit for displaying the radio communication tags.