PURPOSE: To prevent the deterioration of printing quality, by providing a feed means for feeding booklets in a page open state, a moving means for moving a printing means and a guide member for allowing a printing means to be spaced apart from the booklets when passing on a seam.

CONSTITUTION: A printing head 21 being a printing means supports a guide roller 23 so as to move along a printing head guide 22 being a guide member in a sliding state. A passbook is fed in a direction parallel to a seam 12 and the printing head 21 is moved to a position desiring to print the line of the passbook by the driving of a printing head motor 4 to perform printing operation under the control of a control means but a projection 22b is provided to the guide surface of the printing head guide 22 at the position opposed to the seam 12 and the guide roller 23 is brought into contact with said projection 22b under rotation to allow the printing head 21 to be spaced apart from the passbook P. Therefore, generation of jamming by the collision of the printing head 21 with the built-up part of the seam 12 and an ill effect generating disturbance of printing can surely be prevented.