PURPOSE: To obtain excellent mass productivity, operability, and maintainability by providing a RAM for changing printing position and a phase adjusting circuit.

CONSTITUTION: A CPU in a control section receives printing position adjusting data of print heads H1-Hn from an operation section OP. With integral part data of the printing position adjusting data, addresses of the print heads H1-Hn are converted by a RAM for changing printing position. By reading out dummy data, correction of printing position at dot interval unit is performed. A printing position correction timing with a predetermined dot interval is set by a phase adjusting circuit PC common to the print heads H1-Hn with a data below decimal point, and selected by a selector SE and corrected. Accordingly, the circuit can be simplified and the manufacturing cost can be largely reduced. As printing position adjustment of the print heads can be inputted and set from the operation section, operability and maintainability will be improved remarkably and mass production process and adjusting work time at maintaining can be shortened.