An RFID reader-writer comprising: an antenna configured to transmit and receive electromagnetic waves; a reader configured to read out at least information stored in an RF tag (T) via the electromagnetic waves transmitted and received by the antenna; a housing in which the antenna and the reader are housed, wherein the housing includes external surfaces which are exposed outward; the external surfaces include a first surface , a second surface facing the first surface back to back, and a plurality of side surfaces each being continuous to both the first and second surfaces, the first surface providing a front of the RFID reader-writer, the second surface providing a rear of the RFID reader-writer; characterized in that the first surface includes a part formed as a reading surface enabling the electromagnetic waves to be transmitted and received therethrough, a finger-grip groove , and one of a pair of grip surfaces , the finger-grip groove being located between the reading surface and the one surface and adjacent to both the reading surface and the one surface ; the second surface includes a placing surface , a thumb-attaching groove , and the other of the pair of grip surfaces , the other surface being faced with the one surface back to back, the thumb-attaching groove being located between the placing surface and the other surface and adjacent to both the placing surface and the other surface , the placing surface being provided for stationary use of the RFID reader-writer ; the pair of grip surfaces and one of the side surfaces configure a handgrip used by a user for gripping the RFID reader-writer with a thumb and other fingers, other than the thumb, of the user; and the antenna is disposed inside the housing so as to be faced with the reading surface , such that the antenna enables transmitting and receiving the electromagnetic waves through the reading surface. an antenna configured to transmit and receive electromagnetic waves; a reader configured to read out at least information stored in an RF tag (T) via the electromagnetic waves transmitted and received by the antenna; a housing in which the antenna and the reader are housed, wherein the housing includes external surfaces which are exposed outward; the external surfaces include a first surface , a second surface facing the first surface back to back, and a plurality of side surfaces each being continuous to both the first and second surfaces, the first surface providing a front of the RFID reader-writer, the second surface providing a rear of the RFID reader-writer; characterized in that the first surface includes a part formed as a reading surface enabling the electromagnetic waves to be transmitted and received therethrough, a finger-grip groove , and one of a pair of grip surfaces , the finger-grip groove being located between the reading surface and the one surface and adjacent to both the reading surface and the one surface ; the second surface includes a placing surface , a thumb-attaching groove , and the other of the pair of grip surfaces , the other surface being faced with the one surface back to back, the thumb-attaching groove being located between the placing surface and the other surface and adjacent to both the placing surface and the other surface , the placing surface being provided for stationary use of the RFID reader-writer ; the pair of grip surfaces and one of the side surfaces configure a handgrip used by a user for gripping the RFID reader-writer with a thumb and other fingers, other than the thumb, of the user; and the antenna is disposed inside the housing so as to be faced with the reading surface , such that the antenna enables transmitting and receiving the electromagnetic waves through the reading surface. <EOS>