PURPOSE: To print a line containing ordinary characters and large characters in a mixed state by the necessary min. number of times of printing operation, by a method wherein the whole of an one-line printing image is considered to be as one line, and printing and line feed are repeated by the dot width of a printing head from the uppermost position of a large character to perform printing.

CONSTITUTION: The number P1 of dots up to the uppermost end of a large character 12 are added to the present feed quantity (f) and printing paper is forwardly fed by the corresponding quantity. Next, the data of (n) dots equal to the number of head pins, that is, the printing data of the first bus B11 is edited from the position m'=0 from a printing start upper end and printing is performed without discriminating an ordinary character 11 in handling. Subsequently, the editing printing of the second bus B12 of the underside from m'=n is performed. At last, since the large character 12 of (m) dots is printed at the number-of-dot (n) unit of a printing head, the feed quantity up to the next line is calculated as a value, which is obtained by adding P1 to the surplus m.mod.n calculated by dividing (n) by (m), being the distance up to the beginning of the next line. By this method, even when the large character is mixed, printing can be performed by the necessary min. number of times of printing operation.