An image printing method and system. Information of printing paper size, image size to be printed and printing position is inputted by user. On the basis of the information, a control circuit determines the number of data to be printed in the primary scanning direction as well as the number of data for blanks at both sides and additionally determines the number of lines for printing in the secondary scanning direction as well as line numbers for processing and succeeding blanks. In the primary scanning, the data to be printed is supplied to a thermal head together with the data for the blanks. In the secondary scanning, a printing sheet is transported idly for the blank portions. The thermal head is electrically energized in the printing portion for printing the image at a predetermined position on the printing paper.