A weather strip for a motor vehicle, which is capable of being attached to a flange provided in an opening portion of a vehicle body or a closing member for closing the opening portion irrespective of a configuration of the flange. The weather strip includes a base portion in which the flange provided in the opening portion or the closing member is adapted to be inserted, and a seal portion integrally formed with the base portion for sealing between the opening portion and the closing member. An extension wall extends from an end of an outer side wall of the base portion by way of a bending part. The extension wall is bonded to a body panel defining the opening portion or the closing member, which is adjacent to the flange, with a double-sided adhesive tape.