As is well known, a reflected body varies in visual color according to illuminating and viewing conditions. Recently, interior decoration materials are in colorful use. Then, interior decoration materials vary in visual color according to illuminating and viewing conditions.We report results of some goniophotmetric color measurements on interior decoration materials.Change in color, when illuminating and viewing conditions are varied, have been investigated with the goniophotometric colorimeter.If we measure glossy color materials in the direction of specular reflection, the color of reflection light becomes similar to a light-sourse color on a chromaticity diagram.If we measure diffusible color materials, the color of reflection light does not vary on the chromaticity diagram.Color differences according to illuminating and viewing conditions are shown large in the glossy color materials.Color differences in the diffusible color materials does not vary under the illuminating and viewing conditions.