To provide an ink ribbon cassette, which can apply a certain fixed tension to an ink ribbon.

Between the case main body 42 of an ink ribbon cassette 10 and its cover 44, at the places corresponding to an ink ribbon R wound around a delivering core 22, annular frictional members 60a and 60b are fixed so as to come into contact with both the widthwise edge faces of the ink ribbon R wound around the delivering core 22. Since the distance 60c between the frictional members 60a and 60b is slightly narrower than the width of the ink ribbon R, when the deliverying core 22 rotates, a nearly certain fixed frictional force develops between both the edge faces of the ink ribbon R wound around the delivering core 22 and the frictional members 60a and 60b, resulting in developing a tension in the ink ribbon R.