Abstract: An ink ribbon cassette which is adapted to be demountably loaded on a recording apparatus having a recording head capable of recording information on a recording medium supported by a platen, the ink ribbon cassette has the following parts: a substantially box-shaped casing constituted by an upper case and a lower case which are connected to each other at their vertical walls, the casing having a first side wall facing the platen and a second side wall opposing the first side wall, a recessed portion formed in one end of the first side wall and capable of receiving the recording head, engaging portion provided on the second side wall and adapted for engagement with retaining member on the recording apparatus, a pair of through holes constituted by pairs of apertures formed in the portions of the upper and lower cases adjacent to the first side wall, the through holes being adapted for receiving locating members on the recording apparatus so as to locate the ink ribbon cassette, and a path of an ink ribbon ext