PURPOSE: To always obtain constant ink quality by judging the completion of printing at every one line and controlling a drive mechanism on the basis of the temp. of a printing mechanism at the point of time when the printing of at least one line is completed and driving a printing head or a platen to correct a printing gap.
CONSTITUTION: When data is transmitted from an external apparatus and the content thereof is judged as command data, the dot pattern data read from an ROM 34 on the basis of the printing data stored in an RAM 35 is stored in a print buffer region 35c. Next, the dot pattern data of one dot row is read to count the number of the printing dots of one dot row and the dot pattern data of the dot row is printed by a printing head 2. When the printing of one line is completed, the gap correction value depending on the temp. of the printing head 2 corresponding to the count value of a memory region 35a is read from a predetermined value region 34c and the printing head 2 is brought into contact with or separated from a platen 1 to adjust a printing gap.