A control apparatus 10 has a housing containing an IC memory 25 of an RFID tag 20 as a memory element. The RFID tag 20 has an antenna 21 so as to close the housing. The antenna 21 may be attached to an outside of the housing so as to transmit and receive a radio wave to and from the outside of the housing and is connected to the inside of the housing in a closed state via a lead wire insulated from the housing. The housing may be made of a metal with a removable metallic cover formed at a part thereof to allow transmission and reception of the radio wave. The control apparatus 10 may have an RFID tag counterpart section 14 with an antenna 16 so that the RFID tag 20 is electrically insulated from a control circuit of the control apparatus 10.