PURPOSE: To reduce the number of assembling processes and to automate assembling, by clamping both ends of a plate material having each mechanism set thereto to a frame from above by screws and pushing a platen having a paper feed mechanism united therewith in the frame from above with springiness to engage the same with said frame.

CONSTITUTION: A type sheet receiver 9, an electromagnet 4, a hammer 6 and a motor 14 are formed into one set to be clamped to a frame 1 from above by screws. A platen 11 having a paper feed member set to the lateral part thereof is also clamped to the frame from above by an one-touch system utilizing springiness and an ink roll 13 is further inserted in the frame 1 from above at a place positioned on the side opposite to the platen 11. A reversal preventing lever support supporting a reversal preventing lever 24 is also clamped to the frame 1 from above by a screw. Therefore, assembling can be easily performed and the number of processes can be reduced. Further, assembling is also automated in an extremely easy manner and assembling cost becomes inexpensive.