Reading apparatus and reading apparatus case

A reading apparatus case for attaching a reading apparatus body,

• the reading apparatus body including
• an antenna element,
• a substrate including a ground plane that serves as a reference potential of the antenna element and a communication circuit that transmits and receives a radio signal to and from an RFID tag via the antenna element, and
• a body case that accommodates the substrate,
• wherein the body case has a plate-like shape having a length in a first direction that is shorter than a length in a second direction and a length in a third direction, where the first direction is a thickness direction of the substrate, the second direction is a long-side direction of the body case when viewed in the first direction, and the third direction is a short-side direction of the body case when viewed in the first direction,
• the reading apparatus case comprising:
• a parasitic element that is disposed apart from the substrate in the first direction and is disposed so as to overlap both of the antenna element and the ground plane when viewed in the first direction, the parasitic element resonating when the antenna element is excited,
• wherein a length of the parasitic element in the second direction is shorter than ½ of a wavelength of an operation frequency that is used to transmit and receive the radio signal.