PURPOSE: To prevent reduction in the number of lines usable for synthetic characters by selecting an emphatic pattern according to a pattern selection information contained in an emphatic expression starting function stored in a line buffer to be synthesized into a character pattern train for printing.

CONSTITUTION: An emphatic expression starting function and an emphatic expression ending function are stored freely into a line buffer 1 sandwitching a print character code train for performing an emphatic expression. The emphatic expression starting function contains selection information X' of the emphatic pattern. A control circuit 5 gives the logic 1 to an AND gate 6 when the emphatic expression starting function is generated while storing selection information X' into an address counter 9. With such an arrangement, an emphatic pattern dot train is ORed with a pattern character dot train with an OR gate 7 only with respect to the print character code sandwitched through a gate 6 by the emphatic expression starting function and the emphatic expression ending function.