PURPOSE: To prevent printing quality from being lowered due to wrinkles of an ink ribbon, by a method wherein tension rollers each of which has an axis intersecting the axis of a platen are provided on both sides of an ink ribbon, and are pressed against the platen while being rotated in opposite directions.

CONSTITUTION: When the tension rollers 10a, 10b are rotated in opposite directions of arrows while feeding a printing medium 3 and the ink ribbon 4 by driving a take-up side roll 8, the ribbon 4 is pulled by the rollers 10a, 10b formed of a soft rubber, whereby wrinkles are prevented from being generated. To secure and stabilize the contact of the rollers 10a, 10b with the ribbon 4, the rollers 10a, 10b are formed in the shape of a hour-glass conforming to the outer periphery of the platen 1, and are provided on the letting-out side of the ribbon 4 with respect to a thermal head 2. Accordingly, even when an ink ribbon having a large width is used, printing quality is prevented from being lowered due to wrinkles of the ribbon.