For the purpose of improving saving energy of building from viewpoint of roofing system, we focused on the contribution of waterproofing system with thermal insulation performance, and the effect of color difference on waterproofing system were measured and evaluated by using test specimens exposed in the outdoor environment. The test specimens were 8 types with a various color of top coating. The outdoor temperature, solar radiation and the temperature between surface-inside of test specimen were measured in summer and winter season. In case of strong solar radiation, the surface temperature of waterproofing membrane increased in the dark color topcoating. In case of color effect between outside and inside of test specimen, the ratios of thermal insulation on outside-inside in the test specimen were no significant difference by color difference. On the other hand, the dark color top coating in inside-outside showed higher temperature difference more than that of light color. The surface temperature on waterproofing membrane and the surface-air temperature difference against solar radiation was calculated from brightness of color. It was concluded that the color on waterproofing membrane contribute to energy saving in the summer more than winter.