To obtain an ink ribbon carriage driver of thermal transfer imaging apparatus in which occurrence of banding, jitter and cogging is prevented by eliminating variation of torque completely at the time of carrying an ink ribbon thereby sustaining the tension thereof at a constant level.

A fluid coupling 80 is provided, as a torque limiter, in the way of a drive transmission for carrying an ink ribbon R by transmitting the rotation of a winding motor 44. The fluid coupling comprises a drive side plate 81 being fixed to the output shaft 44A side on the winding motor side, and a driven side plate 82 being fixed to the output shaft 44A on the drive gear 46A side oppositely to the drive side plate, wherein the lower part of both plates is placed in a fluid receiver 83 so that viscous fluid 84 being contained therein enters between both plates. A silicon based oil represents the viscous fluid 84 and #300-#30000 is employed practically.