The disclosure relates to an apparatus for communicating with an RFID tag: including a radio communication device; a tag number estimation portion configured to estimate the number of RFID tag circuit elements in a peripheral area of the apparatus; a storage device configured to store a list of identification information of each of a plurality of RFID tag circuit elements; and a mode switching portion configured to switch a mode into a plural tag detection mode in which identification information is sequentially specified in the list stored in the storage device before the RFID tag circuit element corresponding to the specified identification information is detected through the radio communication device, or a response determination mode in which identification information is obtained from each of all the RFID tag circuit elements in the peripheral area through the radio communication device.