PURPOSE: To improve the conveying accuracy of a heat sensitive recording material and to effectively position it by outputting a pulse signal from an encoder based on the rotation of a driven roller, and determining a heat treating timing of a recording head based on the signal by control means.

CONSTITUTION: A pulse motor 22 is rotated at a constant speed with a pulse signal SM output from a controller 26, and a platen roller 12 is also rotated at a constant speed. A heat sensitive photosensitive material 16 is conveyed to a gap between the roller 12 and a thermal head 28, and a heat generator 30 generates heat to record an image. On the other hand, a driven roller 38 is rotated in response to the conveying state of the material 16. Its rotating state is read by an encoder 56 through a rotational shaft 40, a pulse signal Se is output to a counter 60, and the image is recorded. Since the conveying state of the material 16 is detected by the roller 38 to record the image, even if the material 16 is elongated or contracted, or a slip, etc., occurs at the time of conveying, the image can be always recorded at a suitable position. Even when coloring layers are colored, the image can be accurately recorded, and no color misregistering occurs.