A method of setting the copying conditions of a color copying machine includes the steps of scanning a test chart having density patterns in three primary colors, to detect three color components of the light reflected from the test chart, based on which three color exposures are obtained. The test chart is scanned again to make a color copy thereof, and the color copy is scanned to detect three color components of the light reflected therefrom, based on which three color densities are obtained. Relationships between the three color exposures and the three color densities are obtained for the three colors. Based on the relationships, three primary color filters are adjusted to regulate three color components of the light passed therethrough, thereby controlling three color exposures.