To provide a coating composition that gives fabrics and yarns silk character, and a fiber material that is prepared by coating this composition and shows silk characteristics excellent in washing fastness.

This coating composition contains an aqueous solution of low molecular weight polypeptide prepared by hydrolysis of silk fibroin and a water- base binder that hardens at a temperature lower than 120°C and yarns and fabrics are coated with this coating composition hardened to form a resin coating layer. The water-based binder is very suitably acrylic ester copolymer or ester polymer. In addition, far infrared radiating ceramics of less than 3 micron particle sizes and/or fine particles of naturally radioactive rare elements- containing mineral are admixed to the composition whereby the coated yarns and fabrics can develop the thermally insulating properties or negative ion effect. Tourmaline, a mineral of this kind, has the ability to irradiate far- infrared radiation and includes radioactive rare elements.