Adsorption behavior of hydrolyzed wool keratins onto wool fabric was first studied systematically for the purpose of improving the permanent set of a wool fabric. The adsorption isotherm of the keratin onto wool fabric showed a Langmuir type and was found to be influenced by pretreatments such as swelling and reduction of wool fabric. Indeed, by the reduction, the diffusion coefficient of the hydrolyzed keratin was increased by about 10 times as large as that of the untreated wool fabric. It was indicated from the solubility test and washing test that new crosslinks were possibly formed by the adsorption of keratin and the subsequent oxidation. Dyeing behavior of the keratin adsorbed wool fabric was also discussed in terms of the adsorbed amount of hydrolyzed keratin.