A color direct thermal printer has a yellow fixing ultraviolet lamp and a magenta fixing ultraviolet lamp, in order to fix the coloring of color thermosensitive recording material. Behind the yellow and magenta fixing ultraviolet lamps is disposed a reflector, which has portions contacting the yellow and magenta fixing ultraviolet lamps for receiving heat from the yellow and magenta fixing ultraviolet lamps. Outside the reflector, a temperature sensor is mounted which measures tube temperature of the yellow and magenta fixing ultraviolet lamps through the reflector. When the measured temperature is greater than 40.degree. C., the fan is driven and sends air to the yellow and magenta fixing ultraviolet lamps. If the measured temperature is less than 30.degree. C. at the time of operating the starting key, a start of the printing operation is delayed. In the delay, the yellow and magenta fixing ultraviolet lamps are actuated and the tube temperature is raised.