PURPOSE: To provide a printer capable of printing free from the effect of manual deflection and positioning a line of characters accurately on a printing medium by moving a printing head linearly and carrying out printing in accordance with a control signal and a drive signal and setting the printing head to the printing medium with the help of a positioning means.

CONSTITUTION: A printing line is positioned by opening a horizontal indicator of a printing positioning scale and the lower ridge 2b of a front semi-housing 2 in a printer, and then is a printing range set using a printing ruler 18. If a printing switch member 19 is pressed, a drive signal of a motor 4 and a control signal of a printing head 3 each equivalent to a single line of characters are transmitted from a printer 22 via cable 21. The motor rotates moving a printing head 3 to the left along a long window 2a guided by a guide shaft 9 and a guide member 10. Then the printing head 3 is controlled printing a single line of 40 characters on a printing medium 30. When a single line of characters is printed, the printing head 3 will automatically return to a printing start position at right end.