An embroidery data generating device includes an embroidery data storage unit storing data of a plurality of embroidery data, an embroidery data selection unit selecting a desired one of the embroidery data stored on the embroidery data storage unit, a color data storage unit storing data of a plurality of defined colors, and an assignment unit randomly extracting colors from the color data storage unit, the extracted colors being used as thread color data for specifying colors of the color-based pattern portions respectively, the assignment unit assigning the extracted colors to the respective color-based pattern portions composing the selected embroidery pattern. When the embroidery data selected by the embroidery data selection unit includes thread color data of two or more color-based pattern portions having a same color, a randomly extracted color is assigned to the color-based pattern portions so that the color-based pattern portions have the same color.