Recently, the problem of the overdryness in winter has been actualized because of the improvement of the heating level and a ventilation amount increase by the mechanical ventilation equipment, etc. as the high insulation and high airtight house spreads. But, though a variety of dry measures against it have been enumerated, the effect is not quantitatively understood. Then, this research aims to understand the effects of various dry measures quantitatively by the experiment in the laboratory room and the measurement in the real existence house, and to get effective data to contribute to an overdry measures.