A mounting structure has a front pillar and a side member outer panel. The front pillar has a first linear expansion coefficient. The side member outer panel has a second linear expansion coefficient that is greater than the first linear expansion coefficient. The side member outer panel has a first fastened portion, a second fastened portion, a third fastened portion and a fourth fastened portion that form an imaginary region, and a hinge mounting portion that constrains deformation, due to heating, within the imaginary region, and an unfastened portion. The unfastened portion permits deformation, in an in-plane direction, of a region between the first fastened portion and the second fastened portion.