The present invention relates to an internal combustion engine. An object of the invention is to allow an effect produced by an anodic oxide film to be exerted while suppressing a decrease in the combustion rate. A piston 10 includes a cavity portion 20 and a tapered portion 26 that is formed so as to surround the cavity portion 20 on an outer side thereof. The diameter of the tapered portion 26 decreases progressively in the downward direction from the top face side of the piston. A squish portion 28 is formed on an outer side of the tapered portion 26. An anodic oxide film 30 is formed on a surface (tapered face) of the tapered portion 26 and a surface (squish face) of the squish portion 28. The anodic oxide film 30 is not formed on the surface (cavity face) of the cavity portion 20.
