An automobile door with an inner plate and an outer plate wherein the outer plate has a panel formed from a synthetic resin. The panel is attached to a rigid metallic plate, such as steel, through a plurality of fastening holes formed in the longitudinal direction of the synthetic panel. One of the fastening holes near the forward end of the panel has a diameter substantially that of the fastening means. The remaining fastening holes are formed so as to allow longitudinal expansion and contraction of the synthetic panel. A lip portion is formed near the lower edge of the synthetic panel to engage with the inner plate of the door.