An adjustment value applicable to the adjustment of a printing position is obtainable by reading a printing position adjustment pattern printed on a printing medium without requiring the manual operation by the operator. Furthermore, the printing position can be optimally adjusted by accurately scanning the printing position adjustment pattern. For this purpose, an optical sensor is located in the vicinity of the printing head, and the optical sensor is situated near a predetermined position side. The predetermined position side is a pinch roller side where a large restrictive force acts to the printing medium with the printing position adjustment pattern printed thereon.