A thermal transfer printer includes a thermal head, a platen roller which allows the thermal head to be in the head up/down state, an ink ribbon which is drawn between the thermal head and the platen roller, a paper feed roller which can convey a recording paper. A peeling member is disposed on the downstream side of the thermal head in a conveyance direction of the recording paper and can peel the ink ribbon adhered onto the recording paper during printing, and an optical ribbon detecting sensor, which can detect a color discernment marker corresponding to an ink surface of a desired color formed on the surface of the ink ribbon, is disposed between the thermal head and the peeling member.