A recording tape cartridge that can secure the attached region of an RFID in a case is provided including: a case that has an upper case and a lower case and houses a reel around which a recording tape is wound; a restricting wall that is formed at least in the lower case and defines an area in which the reel is housed; a housing portion that is formed between the restricting wall and the corner of the case; and a planar RFID that is provided in the housing portion such that the rotational axis direction of the reel is a normal line direction.