Abstract: In a long trim member for vehicle, a first side wall of an attachment portion is formed with an elastic holding lip and an elastic sealing lip. A second side wall of the attachment portion is formed with an engagement portion and a projection ridge having a slide guide surface. When the attachment portion is pushed, a tip of the elastic sealing lip is kept not in contact with a bottom wall, a projection end of a projected flange portion is slid on the slide guide surface while the elastic holding lip is deformed elastically until the projection end of the projected flange portion passes the peak of the projection ridge. When the attachment portion is pushed further, the elastic sealing lip is deformed elastically in the direction opposite to the pushing direction and the engagement portion of the second side wall is engaged with a lock portion of the flange.