PURPOSE: To execute printing without being conscious of the differences of cut paper and postcard on the software side by modifying firmware built in a mechanism controller without changing a paper sending mechanism.

CONSTITUTION: A command for distinguishing the paper of size A4 e.g. from a postcard is released to software. When the paper of size A4 is specified, printing is executed based on a 1st character of a printer mechanism similarly to an ordinary method, and when a postcard is specified, the 1st character from the software side (a host machine 5) is advanced to the N-th character of a printing mechanism part 1 and printed out on the 1st character of the postcard by the firmware built in a controller part 4 so that printing is executed based on the N-th character (the 1st character to be printed on the postcard) of the printer mechanism.