To provide a weather strip which is excellent in external appearance and sealing performance by solving the problem of the hollow seal part in a prior weather strip in which hollow seal part was low in the surface smoothness and surface brightness and easily wrinkled on folding.

The hollow seal part 13 is equipped with a hollow seal part which is extruded into a desired shape in a thermal plastic elastomer composition by mixing a component (f) (foaming agent) with a thermal plastic elastomer composition and foaming the thermal plastic elastomer composition so that the hollow seal part remarkably improves in the surface smoothness, surface brightness and R following performance by the foaming action of the foaming agent to permit imparting the desirable external appearance and elastic deformation.