To provide a ribbon cassette and a thermal transfer printer for use in the same, which eliminate peeling of ink applied to an ink ribbon in the handling of a ribbon cassette, and prevent a failure such as a paper jam from occurring in a paper sheet, even if the paper sheet abuts on the ink ribbon so as to be rubbed, when the paper sheet is carried in a state in which the ribbon cassette is mounted on the printer.

In the thermal transfer printer S using the ribbon cassette, when the ribbon cassette 1 is mounted on a cassette mounting part 12 in a non-pressure contact state in which a platen roller 14 is separated from a thermal head 13, a ribbon guiding part 6 is located in an upper part of the thermal head 13, and the ink ribbon 2, which is pulled out from a ribbon pull-out port 3d, is located between the thermal head 13 and the platen roller 14; the paper sheet P can be carried between the ink ribbon 2 and the platen roller 14; and when paper sheet P is carried between the ink ribbon 2 and the platen roller 14 in the non-pressure contact state of the platen roller 14, an ink nonapplication part 2c of the ink ribbon 2 is located in a ribbon-folded part 7.