A ribbon cartridge comprises a case, a sliding guide slidably mounted in the case, and an endless ink ribbon enclosed in the case. A greater part of the ribbon is enclosed in the case at a space between the sliding guide and an inlet side of the case. The sliding guide has a front guide plate at an inlet side thereof, and a rear guide plate at an outlet side. The front guide plate has a vertical inlet slit and the rear guide plate has an inclined outlet slit. The ink ribbon is engaged with both the slits so as to correct any twist thereof.