A dissimilar material joining structure includes: a plate-shaped resin member; a plate-shaped metallic member; and a metallic rivet. The rivet includes a shaft, and a head integral with a first end of the shaft, and disposed outside a hole of the resin member hole. The shaft includes: a pillar; an enlarged diameter portion; and a punching portion that is joined to the metallic member via a weld. The hole of the resin member includes: a small-diameter hole portion adjacent to the pillar, and having an inner diameter equal to a diameter of the enlarged diameter portion; and a large-diameter hole portion adjacent to an outer circumference of the punching portion, and having an inner diameter greater than the diameter of the enlarged diameter portion.