The relaxation effects of gardening have attracted attention; however, very few studies have researched its physiological effects on humans. This study aimed to clarify the physiological and psychological effects on high school students of viewing real and artificial pansies. Forty high school students (male: 19, female: 21) at Chiba Prefectural Kashiwanoha Senior High School, Japan, participated in this experiment. The subjects were presented with a visual stimulation of fresh yellow pansies (Viola x wittrockiana "Nature Clear Lemon") in a planter for 3 min. Artificial yellow pansies in a planter were used as the control. Heart rate variability was used as a physiological measurement and the modified semantic differential method was used for subjective evaluation. Compared with artificial pansies, visual stimulation with real flowers resulted in a significant decrease in the ratio of low- to high-frequency heart rate variability component, which reflects sympathetic nerve activity. In contrast, high frequency, which reflects parasympathetic nerve activity, showed no significant difference. With regard to the psychological indices, viewing real flowers resulted in "comfortable", "relaxed", and "natural" feelings. The findings indicate that visual stimulation with real pansies induced physiological and psychological relaxation effects in high school students.