PURPOSE: To accurately make color of a colored resin product coincide with that of a color sample, by incorporating an influence of a filler as a correction factor in a computer color matching method to carry out color matching.

CONSTITUTION: In carrying out color matching by calculating a coloring formula of a resin product containing a filler is calculated using a computer color matching method, an influence of the filler on coloring as a correction factor is incorporated in the calculation process to perform color matching. The amount of the filler is calculated by using fundamental data of each pigment determined from mass tone prepared by using a resin without containing a filler and letdown color sample and filler data obtained from the resin containing the filler and color sample prepared by blending the resin with a white pigment (titanium oxide) or black pigment (carbon black).