Analysis was made of the thermal transfer printing process and 600-dpi high-definition thermal transfer ink ribbons. The results of analysis of this printing process revealed that four factors would play an important role in high-definition thermal transfer ink ribbons: (1) enough rupture strength of ink under printing pressure, (2) adhesive strength of ink and paper, (3) thinning of the ink layer and (4) adhesive strength between the heated part of ink and the basefilm. Using 2.5μm-thick PET film as the basefilm, a 600-dpi highdefinition thermal transfer ink ribbon has been developed, with a 1.3μm-thick thermoplastic resin layer based on ethylene-vinyl acetate copolymer superimposed on a 0.9 μm-thick wax layer. The ink transfer properties of the ink ribbon were evaluated using a pendulum-type viscoelastic properties measuring instrument, with attention focused on the logarithmic decrement -temperature property.