An internal combustion engine includes: a cylinder in which a piston reciprocates; a stepped portion that is formed on an upper end portion of an inner peripheral surface of the cylinder; and a ring member having a cylindrical shape provided to the stepped portion. The thickness of the ring member decreases toward the bottom dear center of the piston, and an outer peripheral surface of the ring member is an inclined surface, where a lower end of the outer peripheral surface is positioned closer to the center in the radial direction of the ring member than an upper end of the outer peripheral surface.