PURPOSE: To improve the operatability of an operator as well as to make any hindrance due to wrong paper insertion, etc., so as to be reduced, by installing an operation guide displaying part at each inserter, and performing a display of the operation guide part to the inserter to be used.

CONSTITUTION: Each red lamp of inserter operation guide displaying parts 2 and 4 is lighted till a printer is made usable. After a while, these lamps turn to blue, showing that the printer is ready to be operatable. When an upper inserter receives a paper receiving command, the displaying part 2 turns to the flicker of a blue lamp, demanding an operator for paper insertion. A lower inserter 3 also does the same manner. During printing to the paper received and its discharge operation, the blue lamp comes to be lighted. When trouble happens in a device, it comes to the flicker of the red lamp. Thus, the operator looks at the display whereby he can easily judge the next work of the device, thus operatability is improved and, what is more, any hindrance due to wrong paper insertion is reducible.