To provide a cassette where printing tape and an ink ribbon are separably provided which enables a ribbon cassette to be easily mounted on a tape cassette.

Guide parts 21a, 21b, 21d, 21e for guiding a ribbon cassette 30 to a tape cassette 20 are provided on the tape cassette 20, and guided parts 31a, 31b, 31d, 31e which are guided by the guide parts 21a, 21b, 21d, 21e are provided on the ribbon cassette 30. In addition, at the time of starting the mounting of the ribbon cassette on the tape cassette and at the time of completing the mounting, the ribbon cassette 30 is guided by the combination of a different guide part and a different guide part, so that the ribbon cassette is positioned.