PURPOSE: To engage a hole provided in a ribbon feeding shaft on the cassette side and a projection of a rotation-transmitting element on the cassette-supporting base side to each other and remove a sag from a ribbon, by automatically rotating the ribbon-feeding shaft by a predetermined angle when the hole and the projection are not engaged with each other.

CONSTITUTION: In the case wherein the ink ribbon cassette 1 is fitted to the casette-supporting base 3, when the hole 11 in the ribbon-feeding shaft 2 in the cassette 1 and the projection 9a provided at the tip of the rotation-transmitting element 9 on the base 3 side are not engaged with each other, the other end of the element 9 pushes an electric switch 13, and the resulting electrical signal causes a ribbon-feeding motor 5 to rotate by a predetermined angle through an electric circuit. By this, the element 9 is rotated by a predetermined angle, whereby the projection 9a thereof and the hole 11 in the shaft 2 are engaged to each other, and the sag of the ribbon is removed.