An internal combustion engine includes: a cylinder in which a piston reciprocates; a cylinder head positioned above the cylinder; a gasket disposed between the cylinder and the cylinder head; a stepped portion that is formed at an upper end portion of an inner peripheral surface of the cylinder and positioned below the gasket; a ring member having a cylindrical shape provided to the stepped portion; and a protrusion portion that is formed in a manner to protrude from the ring member and bites into a lower surface of the gasket.