There is provided a weather strip for use on a sunroof capable of preventing squeak noises being generated in advance between a hollow seal part and a roof panel during traveling of a car by allowing the hollow seal part to satisfactorily follow vibrations of the roof panel. The weather strip ensures sealing property between a roof glass mounted on the sunroof of a car and a roof panel and comprises a built-in base part attached to the roof glass, and a hollow seal part composed of continuous ends integrally formed with the built-in base part and having substantially a circular cross section, a tip end contact part elastically contacting the roof panel, wherein thicker parts protruding inward and being continuous with the built-in base part are formed on the continuous ends of the hollow seal part and protrusions protruding inward are formed on substantially middle parts between the continuous ends and the tip end contact part.