A recording tape cartridge in which, even if impact is applied to a vicinity of an opening due to a drop or the like, a leader pin does not fall out from pin holding portions. The recording tape cartridge has a case which rotatably accommodates a single reel on which a recording tape is wound; an opening for pulling-out of a leader pin attached to an end portion of the recording tape; and pin holding portions formed at an inner surface of a ceiling plate of the case and an inner surface of a floor plate of the case, and holding the leader pin in a vicinity of the opening. A plate thickness of at least regions directly above and directly below the leader pin which is held at the pin holding portions is thicker than an average plate thickness of the case.