An inked ribbon cartridge is removably mountable in a printing machine of the type comprising a support for the cartridge, two transport elements engageable with two spools, respectively, of the cartridge around which the ribbon is wound, two sensing elements for sensing the amount of the ribbon wound on the two spools, respectively, of the cartridge, a ribbon movement reversing mechanism controlled by the sensing elements for determining the direction of the rotation of the two shafts, and a control element for shifting the sensing elements from an operative position in which they sense the ribbon to an inoperative position in which they are disengaged from the spools. The cartridge comprises on a bottom part thereof at least one aperture for access of the sensing elements to the two spools and an opposing part arranged so to co-operate with the control element for the sensing elements as to cause them to shift from the inoperative position to the operative position when the cartridge is mounted on the support of the machine and from the operative position to the inoperative position when the cartridge is removed from said support.