PURPOSE: To prevent a roll sheet from snaking and deviating in plotting when the roll sheet is to be pulled up in the direction of a platen from a roll part.

CONSTITUTION: A roll sheet supporting means 12 for supporting a roll part of a roll sheet rotatably is arranged at a lower part of a platen 2. A pair of tension rollers 20 and 24 are arranged between the roll sheet support means 12 and the platen 2 passing through a clearance having a width slightly wider than the thickness of the roll sheet. When the roll sheet passes through the clearance between the tension rollers 20 and 24, a weak damping force for preventing the roll sheet from snaking is given. A paper pressing sheet 29 is arranged on the tension roller 24 in oscillatory way in the detaching direction. By the pushing force against the tension roller 24, the roll sheet is prevented from being pulled in the reverse direction with respect to the roll sheet conveying direction from the clearance of the tension rollers 20 and 24.