Provided is a method for creating a color scale that can be used as more objective assessment criteria used for the evaluation of the masticatory force by a color-changeable chewing gum by analyzing the characteristics of the color change in the gum along with the progress in mastication in people having toothed jaws. A method for creating a color scale, comprising having a plurality of people having toothed jaws masticate color-changeable chewing gums, obtaining a regression equation for the color presented by the masticated gum and the color difference between the gum before and the gum after mastication, and further, obtaining a regression equation for the number of times of mastication and the color difference between the gum before and the gum after mastication, to thereby obtain the number of times of mastication performed by the people having toothed jaws and the color difference in the color presented by the masticated gum.
