To prevent a sheet such as photosensitive paper from being irregularly heated caused by vapor which can not escape in heating the sheet in a sheet heating device where the sheet is wound round the outer periphery of a heating drum, and the heating drum is rotated to carry the sheet while the sheet is heated by the heating drum.

Rollers 51 to 53 are pressed against the outer periphery of the heating drum 50 at some intervals, and the base ends of plural elastic blades 60 and 70 formed like a wide plate are supported between the rollers and the tips 60a and 70a sides are pressed against at some intervals. When the photosensitive paper S is heated, the vapor generated from the photosensitive paper S is allowed to escape to the outside through space between the respective blades 60 and 70 and space between the rollers 51 to 53 and the blades adjacent to them.