Provided is a thermal transfer sheet enabling printing suitability on high temperature printing to be good. A thermal transfer sheet 100 in which either one or both of a colorant layer 3 and a transfer layer 10 are provided on one face of a substrate 1, and a back face layer 20 is provided on the other face of the substrate 1, wherein a back face primer layer 25 is provided between the substrate 1 and the back face layer 20, and the back face primer layer 25 contains at least one component selected from a silicone resin, a siloxane cross-linked resin, and a silica-introduced resin.