An apparatus according to an aspect of the invention includes: a first table and a second table on which an article with an RFID tag may be placed; a retaining mechanism for selectively retaining the first table and the second table in a state in which the second table is placed on the first table and in a state in which the first table and the second table are apart from each other vertically by a specified distance; a first article detector and a second article detector disposed on the upper surface of the first table and the upper surface of the second table, respectively, for detecting that the article has been placed; and an antenna communicating with the RFID tag, with the directivity aimed upward when the second article detector has detected the article, and with the directivity aimed downward when the first article detector has detected the article.