PURPOSE: To save the labor of an instructor to copy an original from a document to a sheet by controlling the time difference driving of each printing head, enlarging a read original picture, and printing it on the sheet.

CONSTITUTION: When the original is set at an original picture reader 33, and a reading command is issued by using a control switch 4, the original picture is read, transferred to a controller 10 as serial data, and temporarily stored in an RAM 13. Then, each one line of the read original picture is successively enlarged according to the width direction method of a sheet 100 by picture enlarging devices 11 and 12. Then, the enlarged original picture for each one line is data-expanded to a partial original picture to be charged by each printing head 31A-31H by the picture data expanding devices 11 and 12, and stored in the RAM 13. At that time, when a printing command is issued by the control switch 4, the controller 10 controls the driving of a writing feed sheet feeding mechanism 5, and allows the sheet 100 to travel in an X direction at a prescribed speed. Then, the time difference driving of each printing head is operated.