In order to clarify the effect of restriction of solar rays on the anthocyanin accumulation in flower petals of snapdragon, whole or a part of plants was covered with various covering materials. Removal of ultraviolet light by covering the whole plant with some kind of UV-cut plastic film or FIRON did not affect on the anthocyanin content in flower petals. In covering the whole plant with various colored plastic films, the anthocyanin content was lowest under the green film and relatively high under the blue and the purple films. By covering either the flower spike or the leaves and stem except spike with cheesecloth the anthocyanin accumulation in petals was reduced, and the reduction effect was higher in covering the flower spike. The anthocyanin content in flower petals declined with the rise in the rate of shade of flower spikes, and the rate of decrease in the anthocyanin content depended on the cultivars.