PURPOSE: To determine coloring scientifically and speedily by selecting colors from a center zone where colors harmonizing with all colors of four areas visually and laterally successive areas in a color matrix diagram.

CONSTITUTION: The color matrix diagram which consists of four areas sectioned by an (x) and a (y) axis, i.e. a right upper R zone 1, a left upper Y zone 2, a right lower B zone 3, and a right lower G zone 4 is used. Namely, reddish colors which visually harmonize are gathered and arranged in the R zone 1, yellowish colors in the Y zone 2, bluish colors in the B zone 3, and greenish colors in the G zone 4. In addition to those four areas, the center zone 5 is provided in the center and colors (e.g. white, black, gray, etc.) which harmonize visually with all the colors in the four areas are gathered and arranged. For the purpose, plural colors are selected from laterally successive areas to obtain coloring which gives a comfortable impression. Consequently, the coloring is determined scientifically and speedily.