PROBLEM TO BE SOLVED: To provide a regeneration method of a pathogenesis factor production inhibition fiber capable of recovering a function of inhibiting production of pathogenesis factors after washing.SOLUTION: The invention relates to a regeneration method of a pathogenesis factor production inhibition fiber constituted by a fiber that at least one compound selected from a group consisting of a compound having a phosphate group and a compound having a carboxylic acid group is fixed to the fiber by a chemical bound, including an acid treatment of the pathogenesis factor production inhibition fiber after washing.