A recording tape cartridge of the present invention includes a case, an opening aperture, a guide groove, and a covering member. The case is substantially rectangular and rotatably accommodates a single reel, onto which recording tape is wound. A corner portion of the case, at a front side in a direction of loading into a drive device, is cut away to form the opening aperture, which is for drawing out a leader member attached to an end portion of the recording tape. The guide groove is provided at an inner face of the case, and is inflected. The covering member is formed by a plurality of plate pieces which are joined by (a) hinge(s), and is guided by the guide groove. The covering member slides to open and close the opening aperture.