PURPOSE: To prevent a misregistration of colors even if a color printing is conducted using recording paper of different material, to simplify a paper feed mechanism part, and to lower a production cost by a method wherein a detection part for measuring a frictional force of recording paper is provided in a paper feed path, and the rotational speed of a motor for feeding recording paper forward and backward is controlled by an output signal from the detection part.

CONSTITUTION: Recording paper 18 payed out from a hopper 7 by a pick roller 1 is applied with a frictional force by a friction plate 3, whereby a piece of the recording paper 18 is supplied into a device. The deflection of a detection needle of a pressure plate 2 caused by the frictional force at this time is detected by a detector 6. The detection signal is transmitted to a control part 17. In accordance with the coefficient of friction of the recording paper 18, a slip amount when the recording paper 18 is fed forward and backward while being clamped between a platen 10 and a platen pinch roller 11 and a platen pinch roller 12 is experimentally found. Next, the rotating speed of a platen motor 13 for driving the plate 10 is controlled in accordance with an output signal from the detector 6. In this manner, a feed amount can be kept constant even if the material of the recording paper 18 is changed.