To provide an ink ribbon cassette covering the exposed part of an ink ribbon to prevent adhesion of dust thereto in which dust can be wiped off and a constant tension can be imparted to the ink ribbon.

A case body 42 contains a feed-out core 20 and a winding core 30 and an ink ribbon R is exposed on the side of side wall close to a print head H. Thin planar resilient members 62, 66 are fixed to the outlet 52 and inlet 56 of a case 40 while being pressed against ribbon guide parts 72, 76. The ink ribbon R is clamped between the thin planar resilient members 62, 66 and the ribbon guide parts 72, 76 while being covered with the thin planar resilient members 62, 66 and pressed. Consequently, the exposed ink ribbon R is protected against adhesion of dust, adhering dust is wiped off and a constant tension is applied to the ink ribbon R immediately in front of the print head H.