In recent years, there have been increasing concerns on improving occupants’ thermal comfort, health and productivity through the improvement of indoor environment. The objective of this paper is to examine the effects of foliage plants and artificial plants on human physiological /psychological responses by panel experiments in a full scale room model. In this experiment, environmental parameters such as air temperature, humidity, illuminance and so on were kept constant independently, whether the plants/artificial plants were present or not. Two subjects at a time were asked to stay in said chamber. Then questionnaire evaluation and performance tests were conducted during a period of 170 minutes per experiment. A “green amenity effect” such as physiological/psychological improvement was shown by the questionnaire. It confirms that the condition of having plants in an indoor environment improves the performance of text typing and the similar tendency is seen for addition. And, disposition of some foliage plants in an office can bring positive economic effects.