PURPOSE: To make a printing having the same hammer pin length usable and to simplify gap setting mechanism of a platen and the printing head, by forming a platen from a polygonal and polyhedral structure supported in a rotatable manner and using each of the surfaces thereof as a paper holding surface differentiating the gaps between the front surface of the printing head and the paper holding surfaces at every surface.

CONSTITUTION: The radii of the respective sides of the peripheral surfaces of a platen 1 having a polyhedral structure are made different mutually and a plurality of paper holding surfaces 11W1n different in the distance from the front surface of a printing head 3 are formed to the respective sides. A knob 2 is operated corresponding to the thickness of paper to be printed to angularly rotate the platen 1 and the specific paper holding surface is arranged under the head 3 and supports the paper to perform printing by the head 3. By this construction, the paper holding surface for supporting thin paper of the platen 1 to the printing head 3 is high and the paper holding surface supporting thick paper is set low and, therefore, the paper holding surface to the head can be variously altered by the rotary operation of the platen 1.