A mount sheet having a plurality of radio tags attached at an interval to it is run over a radio communicating section. The radio communicating section has a metal member providing a conveying surface with a slit formed therein. A dielectric member is arranged on a lower surface of the metal member with a projecting section inserted into the slit and, by doing so, the top surface of the projecting section is set flush with the top surface of the metal member. An antenna of the radio communicating section is located beneath the projecting section of the dielectric member and this antenna is held within the metal case. When any radio tag being an object of a radio communication is located over the slit, the radio communicating section positively makes radio communication with the radio tag through the antenna.