To install a weatherstrip in a cowl louver 7, even if a part of a neck part 15 and an installation part 16 of the weatherstrip 6 is not cut off, in a weatherstrip installing structure for installing the weatherstrip 6 composed of a hollow seal part 14, the neck part 15 and the installation part 16 and constituted of an elastic material, in the cowl louver 7.

The cowl louver 7 is formed with a recessed groove 17 for inserting the installation part 16 of the weatherstrip 6, and is formed with claw part 21 and 22 for locking outside parts 23 and 24 in the width direction of the installation part 16.