To make the printing on a form performed appropriately even when the form is conveyed meanderingly due to the abrasion of a conveyance means, and to maintain the quality of printing.

If the inclination of a label 1 at the printing position of a printing head 5 used for a printing means which is generated due to the meandering of the label 1 as the former at the conveyance caused by a platen roller 6 used for the conveyance means is detected by former end detection sensors 10a, 10b used for detection means, a dot image which is developed in RAM used for a storage means is made to be matched with the inclination detected by the form end detection sensors 10a, 10b, by a control part 11 used for a control means. Based on the printing data according to the dot picture with which the inclination was matched, the printing on the label 1 is performed by the printing head 5.