At both sides of an opening of a cassette case, there are formed tape guides having guide faces, and a magnetic tape is stretched between the guide faces. First and second cam grooves for guiding an open/close lid which covers the stretched magnetic tape are provided at opposite sides of the cassette case so as to guide first and second slide pins projected from opposite sides of the open/close lid. A biasing member is provided near one of the cam grooves for urging the open/close lid in a closing direction. A gap between an inner face of a curved portion of one of the first cam groove and an outer peripheral face of the first slide pin is different from a gap between an inner face of the curved portion of the second cam groove and the outer peripheral face of the second slide pin.
This is a divisional of application Ser. No. 09/979,011 filed Nov. 15, 2001 now U.S. Pat. No. 6,866,215, which is the National Stage of International Application PCT/JP00/03136, filed May 16, 2000; the disclosure of which is incorporated herein by reference.
