A weatherstrip includes a welt section in a substantially letter U shape cross section attached to a flange, and a trim lip formed on an outer surface of an inner side wall section to cover an end edge of a vehicular body trim. The flange is held from both sides by holding lips extending obliquely toward a summit section from the inner surfaces of the respective side wall sections. A projection section is projected on a back side of the outer holding lip. When the flange is fitted, the outer holding lip is struck on the projection section and positioned.