Objectives: In the present study, we aimed to clarify the psychological effects of shinrin-yoku (taking in the atmosphere of the forest) by conducting field experiments. Methods: The experiments were conducted in 19 forested and urban areas in Japan during the 2007–2010 period. Twelve male students participated at each of the 19 areas (a total of 228 persons). Subjective ratings of “comfortable-uncomfortable”, “soothing-stimulating”, and “natural-artificial” feelings were conducted after each of the participants had viewed the scenery for 15 min in the forested and urban areas. A postviewing questionnaire on “stressed-refreshed” feelings was also administered and the Profile of Mood State (POMS) questionnaire was employed to assess six aspects of mood before and after viewing the sceneries. Results: The forest environments were perceived as significantly more “comfortable”, “soothing”, and “natural” than the urban environments after viewing the sceneries. The score for “refreshed feeling” was also significantly higher in the forested areas. The score for the “vigor” subscale of POMS was significantly higher after viewing the scenery in the forested areas, whereas the scores for negative feelings such as “tension-anxiety”, “depression-dejection”, “anger-hostility”, “fatigue”, and “confusion” significantly decreased. Conclusion: Collectively, these results suggest that the forest environments have significant beneficial and relaxing effects on human’s moods compared with the urban environments.