PURPOSE: To improve the printing workability by providing an automatic centering/setting means for automatically centering the printing data in the longitudinal and lateral directions in conformity with the size of a printing part for every tack label of a cut form sent into a printing machine.

CONSTITUTION: The printing apparatus 1 has a printer 8. A cut form having a plurality of tack labels aligned and attached in the longitudinal and lateral directions is fed to the printer 8. Characters (addressed, names, etc.), symbols, figures or the like are printed on each tack label under the control by a central processing device 4. In this case, a main body 1a of the printing apparatus is provided with an automatic centering/setting device 8a which automatically centers the printing data of a combination of the characters, symbols, figures and the like to be printed at a printing part in conformity with the size of the printing part for every tack label of the cut form in the longitudinal and/or lateral directions. Moreover, the apparatus is provided with an automatic en-size converting device 8b which converts at least a part of the printing data to en-size characters if the length of the printing data is larger than the width of the printing part.