Provided is a thermal transfer printing device wherein an overlapping portion is less noticeable even in the presence of an external disturbing factor caused by variations in characteristics or the like of an ink sheet and paper. This thermal transfer printing device 1000 is provided with: a divided image data-obtaining unit 21 that obtains data of a first-screen calibration image 70a including gradation value data of a plurality of first-screen calibration patterns 71a, and data of a second-screen calibration image 70b including gradation value data of a plurality of second-screen calibrationpatterns 71b; a density adjustment parameter storage unit 36 that is for calibration and that stores a plurality of density adjustment parameters having respective correspondence relationships with the plurality of first-screen calibration patterns 71a and the plurality of second-screen calibration patterns 71b; a density adjustment process unit 32 that adjusts color gradation value data of a first-screen overlapping portion 72a and gradation value data of a second-screen overlapping portion 72b, using density adjustment parameters having correspondence relationships therewith; and a printingunit 50 that performs printing on recording paper 14 so that a plurality of printing calibration patterns 75 each including a printing overlapping portion 76 in which the first-screen overlapping portion 72a and the second-screen overlapping portion 72b overlap, on the basis of data related to color densities adjusted by the density adjustment process unit 32, wherein the color density of the printing overlapping portion 76 printed on the recording paper 14 varies between among the printing calibration patterns 76.