A weather strip (50) has: a body section (51) which extends along a door sash (12) and an edge of a door body (11); a ridge section (52) which extends from the body section (51) so as to rise toward the outside of the vehicle; and an extension section (53) which extends at the root of the ridge section (52) from the body section (51) so as to be capable of being located between a door mirror (14) and the surface (23) of an upper piece section (21), the surface (23) facing the outside of the vehicle. The extension section (53) is gripped between a gap absorbing member (33) and the surface (23) of the door sash (12), the surface (23) facing the outside of the outside of the vehicle. Also, a protrusion section (54) is engaged with an engagement recess (55). The weather strip (50) is held down not at a fitting section (56) but also at the extension section (53) and the protrusion section (54). As a result, the weather strip (50) is less likely to come out of the door sash (12).