The function of environmental humidity control (B-value) of Nylon6 fabric, Rayon fabric and Tencel fabric was evaluated as the representative of commodity textiles showing a moisture sorption-desorption. B-value of these textiles was depending on their moisture sorption; the nearly same value as Woolen fabric for Rayon fabric, the somewhat higher value than Cotton fabric for Tencel fabric and the considerably lower value than Cotton fabric for Nylon 6 fabric were obtained at the specimen's weight of 0 to 20g / a volume of closed vessel(V = 0.012m³). The change of moisture sorption in each textile during measurement of B-value was given as the difference between the moisture sorption isotherm at the side of lower temperature (25℃) and the moisture desorption isotherm at the side of higher temperature (35℃). Based on this fact, the calculated relation curve of B-value and specimen's weight (g/V), using the moisture sorption isotherm at 25℃ and the moisture desorption isotherm at 35℃, agreed well with the observed one. Furthermore, the B-values at 7.5g/V of a mixture composed of various fabrics including fabrics in previous paper[Sen'i Gakkaishi, 52,234 (1996)], basically, was given as the average value with a mixed ratio of the B-value at 7.5g/V of its each component. Moreover, even if the relation curves of B-value and W0/V vetween each component in a mixture was markedly different, it was given as the conversion B-value for a kind of component which was determined in this paper.