To improve the preservation characteristics of an ink ribbon for heat transfer, the reliability in reading of a sensor mark and also the productivity of the ink ribbon.

The ink ribbon 10x for heat transfer has an ink layer 2 consisting of a dye and a binder resin, and the sensor mark 3 consisting of carbon black and the binder resin, on one surface of a sheet type substrate 1 while having a back coat layer 5 on the other surface thereof. In such an ink ribbon for heat transfer, a weight ratio of the carbon black forming the sensor mark 3, to the binder resin is specified so as to be 1.5-3.0.