An ink ribbon for thermal transfer printer comprising a foundation and a thermal transfer layer, said thermal transfer layer comprising a colored layer containing a wax-like substance as a main component of the vehicle thereof, and a thermoplastic adhesive layer having a film-forming property provided on the surface of the colored layer, said thermoplastic adhesive layer having a melt viscosity of 1.times.10.sup.4 to 5.times.10.sup.6 cP at a temperature by 40.degree. C. higher than the softening temperature of the adhesive layer, a softening temperature of 45.degree. to 90.degree. C., a solidifying temperature of 25.degree. to 65.degree. C. and a temperature difference of at least 10.degree. C. between said softening temperature and said solidifying temperature. The thermal transfer ink ribbon provides clear images not only on a smooth paper but also on a rough paper even in a high-speed printing or even on printers with different peeling conditions.