To increase the ratio of an amount of information that can be included to an area occupied by a track pattern.

A track pattern storing part 2 stores track pattern information set with gradation density of three or more values, an image data compositing part 3 composites bitmap data of the track pattern information with bitmap data of image information to generate print data, and an image printing part 1 prints the print data. This obtains an effect that can drastically increase an amount of information that can be included in the track pattern.