Abstract: A cartridge for a carbon ribbon of an office machine, comprises a container in which are rotatable a feed spool and a take-up for the carbon ribbon. The carbon ribbon passes from the feed spool out of a first aperture and back into the container through a second aperture of the container. The take-up spool is rotatable mounted on a support which is pivoted in the container about a fixed axis. The container has at the bottom an opening arranged in correspondence of a toothed roller also rotatable in the container and adapted to receive a driving shaft of the machine for the rotation of the toothed roller. A spring biases the support of the take-up spool against the teeth of the toothed roller for holding the outermost turn of the carbon ribbon wound on the take-up spool in engagement with the toothed roller, so that for the rotation of the take-up spool by the toothed roller, the ribbon is unwound from the feed spool to the take-up spool.