The recording media cartridge includes a lid which is mounted on an upper half with rotary shafts provided at both side ends thereof in a manner capable of opening/closing for a front surface opening portion on a case body formed by coupling the upper half and a lower half, and a lid urging member having an inflection arm portion between a support end portion for engaging the member to the upper half and an anchor end portion anchored on a front edge inner surface, wherein the inflection arm portion of the lid urging member is brought into contact with the upper half at least at one portion during the open state and is deformed through inflection at the inflection arm portion by making the contact portion as a point of inflection, and the lid is urged in a rotating direction for closing.