An interrogator has antennas for communicating information in a non-contact manner with an IC circuit part of a RFID circuit element to be interrogated, a control circuit, and a radio frequency circuit including a directivity switching control portion. In accordance with at least said communication distance of information communication, the control circuit and the directivity switching control portion perform control so as to broaden the directivity of the antennas when said communication distance is short and to narrow the directivity of the antennas when said communication distance is long.