We compared the electroencephalogram, blood pressure, and sensory evaluation inspectioni several color of Petunia hybrida to analyze the physiopsychological effects of a plant. Considering occipital is related to visuosensory field, green color is thought as mild visual stimulator unlike to pink color. The results are coincident with the well-known facts that green color is less stimulating color. It is also accorded with the sensory evaluation results that green color showed te feeling of blue and stable. In case of green color is showed the feeling of blue and stable. In case of green color the generatioin of alpha waves increased according to the increase color area. Therefore it is thought that green color helps decrease of visual stimulation and increase in visual stability. However it is thought that pink has less physiopsychological effects on human beings depending on area sizes than green has.