Abstract: A piston for a reciprocating internal combustion engine includes at least one pressure ring installed in an outer surface of the piston main body adjacent to the piston head. The pressure ring has a double-angle butt end construction comprising an outer circumferential surface slidably contacting the inner circumferential wall of the cylinder, a radially extending first butt flat end face, and a side wall facing the combustion chamber side, namely the high-pressure side, of the engine piston chamber. Only a corner portion formed on the combustion chamber side of the pressure ring by the outer circumferential surface, flat end face and side wall is partially cut away to form a notch which is contiguous to the outer circumferential surface, end face and side wall.