A side panel for an automotive body includes a unitary panel having a side sill, a roof rail, and a pillar integrally joined to each other. The pillar extends from the side sill to the roof rail, and each of the side sill, the roof rail, and the pillar are made of fiber-reinforced plastic. At least one of the side sill, the roof rail, and the pillar has a recess concave transversely outwardly relative to the automotive body. The recess has an opening that opens transversely inwardly relative to the automotive body. The recess is defined by two side walls bent from flanges and extending transversely outwardly relative to the automotive body, and a bottom wall joined to the side walls. The side walls have portions joined to the flanges, the portions of the side walls being thicker than the bottom wall.