PURPOSE: To print a contracted printing pattern in a column direction by thinning dot data at even or odd number as counted from one end of dot column data for each dot now data constituting font data, and forming new printing pattern.

CONSTITUTION: When a printing is started, dot column data of one column for forming font data 4 is read, and stored in an input register 5. The dot column data 5a is as second column data from left for forming, for example, character pattern 2. One end of the dot column data 5a stored in the register 5, for example, at even number of dot data as counted from the upper end is thinned, and stored in an output register 7. As a result, the number of the printing dot 1b is contracted by 1/2 in a column direction, stored in the register 7, and transferred to a buffer memory 8 at a next timing. When similar process is executed for all the font data for forming the pattern 2, new printing patter 9 contracted at 1/2 in column direction is obtained, transferred to the printer 10, and printed.