In laser thermal transfer printing using a dye sublimation type medium, a high definition and continuous tone image can be obtained easily because a laser light focuses on a small spot, and its heat energy can be controlled by pulse width modulation. In this study, we investigated dye transfer depth from the ink layer to elucidate the mechanism of dye transfer. Ink donor sheets composed of a laser light absorbing layer and several color sublimation dye layers were prepared. The results confirmed that the dye was transferred from the surface ink layer in contact with the receiving layer, and also from the bulk of the ink layer in the range of low and high recording energy, respectively. By microscopic measurement after laser irradiation, we find that dye transfer from the bulk of the ink layer corresponds to the creation of a small hole at the ink's surface. Temperature transition in the ink layer by numerical calculation was different depending on the contact condition with the receiving sheet and the spot size of the laser light.