PURPOSE: To continuously hold the display, etc. by mechanical means wihtout using keep relay, and release this continuous hold state mechanically by manual manipulation of operating member.

CONSTITUTION: When abnormaamlity of paper jamming sheet transfer is detected, a solenoid 6 is excited, and a detent holding member 4 turns in direction a around a pin shafrt 5. As a result an operating member 2 which has been locked so far by an end shaft part 3a of a stepped pin 3 wich abuts against a side edge part 4b of folding piece 4a of a member 5 begins to move in direction b due to elastic tension of a spring 7. The end hbead part of the operating member 2 hits against an opnning-closing cover 12 for removal of jammed paper. At the same time, the member 4 turns in direction a, where it is locked by shaft part 3a. Simultaneously, a microswitch 9 is turned on, and jamming is displayed. In order to remove the jammed paper, the cover 12 is turned and opened. After removal, when the member 2 is pushed in by hand, said lock state is released.