The change in water content within a cloth during contact with air of various relative humidity levels was measured by weighing the cloth exposed to humid air flow. The experimental results were analyzed with a model of moisture absorption which consists of the moisture transfer within air, the adsorption and desorption reactions at the surface of cloth and the moisture transfer within the cloth. The mass transfer coefficient of moisture within air, the adsorption and desorption rate constants and the mass transfer coefficient of moisture within the cloth were determined. Though the adsorption rate constants of cloths made of natural fibers (wool, silk and cotton) was about twice that of those made of synthesized fibers (nylon and polyester), the variation of the adsorption rate constants was comparatively small for the fiber species used. The adsorption rate constant varies little with the relative humidity of air, but the desorption rate constants of cloths made of natural fibers increase with the increase in the relative humidity up to 50%. The desorption rate constant varies largely with the clothing material, and that of polyester cloth is twenty times as large as that of wool cloth. The mass transfer coefficient within the cloth decreases rapidly with contact time, and the value of polyester cloth is larger and decreases in less time than other cloth species. The effective diffusion coefficients of moisture within cloths can be estimated from the mass transfer coefficients, and the values were in order between 10^-10 and 10^-9 m²/s. This indicates that the moisture transfer within cloth is dominated by the diffusion of water within fiber. The change in water content within the cloth could be reproduced by the calculation using the air phase mass transfer coefficient, the adsorption and desorption rate constants and the cloth mass transfer coefficient. The mass transfer coefficients obtained here can be applied only to the present experimental conditions, because the moisture transfer within air or cloth is affected by the shape of the cloth or by the structures of the textile and yarn.