A first fiber treatment comprising a functional protein prepared by treating proteins such as collagen with a cross-linking agent and a solvent-base resin; a second one comprising the above functional protein and a water-base resin; a third one comprising a water-soluble organic substance having an average molecular weight of 100 to 20000 and a reactive modifier; a fourth one comprising the above functional protein and a reactive modifier; and products such as fibers and textile goods treated with one of the treatments.