A data processing device processes embroidery data for a sewing machine capable of embroidering and print data for a printer that prints a pattern on at least a portion of an embroidery formed by the sewing machine. The data processing device includes an embroidery data generating unit for generating region data defining a plurality of embroidery regions based on color image data and the embroidery data defining embroidery patterns respectively applied to the plurality of embroidery regions, a color designating unit for designating a thread color from a plurality of thread colors contained in the embroidery data in order to designate a print-target embroidery region from among the plurality of embroidery regions, and a print data generating unit that generates print data representing an image applied to the print-target embroidery region based on at least part of image data corresponding to the designated print-target embroidery region.