INTERNAL COMBUSTION ENGINE FOR STRADDLED VEHICLE, AND STRADDLED VEHICLE

An obj ect is to suppress a problem caused to an internal combustion engine, including a diamond-like carbon layer provided on an outer circumference of a piston ring, due to a gap between a piston skirt and a cylinder wall not having an appropriate size. A piston included in an internal combustion engine in an embodiment according to the present invention includes a piston head; a piston ring attached to an outer circumference of the piston head; and a piston skirt extending along the cylinder wall from the outer circumference of the piston head. The piston ring includes a diamond-like carbon layer on an outer circumference thereof. The piston skirt includes a slidable portion slidable against the cylinder wall. The slidable portion includes a resin layer in at least a part thereof, the resin layer preventing heat of the piston from being transmitted from the piston skirt to the cylinder wall.