To improve the formability of a fender panel and a front pillar portion, and also to improve their positioning accuracy.

The structure for mounting a fender panel 6 on a cowl top side garnish 4 is applied to a vehicle which composes part of a front pillar with the fender panel 6 by extending the fender panel 6, and mounts the fender panel 6 on the cowl top side garnish 4 arranged so as to extend from the lower end corner portion of a front pane 1 along the front pillar. The cowl top side garnish 4 comprises a base end portion 4a to be fixed to the front pane 1, a vertical wall 4b which elongates upward from the base end portion 4a, and composes a partial surface of the front pillar on the central side of the vehicle, and a gripping groove 13 formed in the upper region of the vertical wall 4b. The fender panel 6 is mounted on the cowl top side garnish 4 by engaging the downward flange 6a of the fender panel 6 with the gripping groove 13.