PURPOSE: To flatten ink attached onto a medium to be printed positively and uniformly by providing an attaching means sticking the medium to be printed onto a belt and a heating means heating the medium to be printed onto the carrying path of the medium through the belt.

CONSTITUTION: The front end of a film sheet 3 is detected by a detecting switch 28, the temperature of a platen 12 and a set temperature are compared by a thermistor 15, a belt 20 is turned when the temperature of the platen 12 reaches the set temperature, and the film sheet is charged by an electrostatic generator 24. The film sheet 3 is held by the belt 20 by an upstream feed roller 16a and an upstream pinch roller 16b, and attached onto the belt 20 by static electricity. The film sheet 3 is brought into contact with the platen 12 equipped with a heater 14 and heated, and after cooled by a cooling platen 17, separated from the belt 20 by a downstream feed roller 18a. The charge of the film sheet 3 separated is eliminated with a charge eliminating brush 29 by means of a downstream feed roller 18a and a downstream pinch roller 18b, and discharged.