PURPOSE: To control vibration to be generated as well as realize the miniaturization of weight reduction of the device by a method in which a hammer portion to generate printing force and one end of a platen to receive printing force are set symmetrically to a supporter in such a way as to cancell forces acting on them.

CONSTITUTION: A platen holder 3 to support a platen 2 is rotatably attached to periphery of the main shaft 4 and the other end 3' is contacted with an adjust cam 6. A hammer blank 7 to be mounted with a hammer 1 is also rotatably attached to the main shaft 4. The other end 7' of a comb form slides with the main shaft 5. In printing condition, the platen 2 is ready to turn toward the direction of arrow A around the shaft 4 by the printing force of the hammer 1, but the other end 3' is contacted with the cam 6, so that a force in the direction of arrow B is applied to the shaft 5. The hammer 1 undergoes a reaction from the platen 2 to turn in the direction of arrow B, and thereby a force in the direction of arrow A is applied to the shaft 5. In this way, the two forces can be cancelled each other out.