The purpose of this study is to determine the humidity of the environment in elderly people's homes in the Niigata prefecture and also the effects of enjoying humidification. Investigations were carried out in 12 homes for the elderly in Niigata and Nagaoka cities through every season, in order to understand how the humidity of their environment varied through the seasons. The measurement terms within each season were for a period of about one week for each individual house and the measurements were performed in the living room and outside the house. Some of the results are as follows. (1) The humidity indoors is low in the winter and the average humidity is 5.1 g/kg; differences between indoor and outdoor humidity varied with time of day. In summer and winter, the difference was greater during the daytime and nighttime than that at daybreak, probably due to influences of cooling or heating equipment. (2) The skin surface hydration of residents was lower in winter in comparison with the other seasons. The humidity sensation perceived by the residents tended toward 'humid' rather than 'dry' with the increase skin surface hydration and humidity. (3) The effect of a humidifier depends on the air tightness and heat insulation properties of the room and the control system of the equipment.