A window frame is constituted by an inner panel, an outer panel and a door sash which are formed by press molding, and a glass run body of a glass run is attached and locked in an attachment groove provided in the door sash. A trim formed separately from the glass run is attached to an interior flange of the inner panel and an interior flange of the door sash so that an exterior holding lip of the trim is brought into pressure contact with an interior holding lip provided on the glass run. A door glass is adapted to be guided to slide by seal lips of the glass run. The interior flange of the door sash and the attachment groove are integrally formed as a single component and the relative positions of these two parts are kept stable.