1. A multi-primary-color display device comprising: a plurality of pixels each including a first subset including red, green and cyan subpixels and a second subset including yellow and blue subpixels; wherein in each of said plurality of pixels, the subpixels included in the first subset are arranged in series in one direction, and the subpixels included in the second subset are arranged in series in the same direction as the subpixels of the first subset; and supposing achromatic colors to be represented by the first and second subsets are called a first achromatic color and a second achromatic color, respectively, a ratio of a difference in luminance between the first and second achromatic colors to a sum of maximum luminances of the first and second achromatic colors is equal to or smaller than about 15% and a difference u′v′ in chromaticity between the first and second achromatic colors is equal to or smaller than about 0.100.