Piston for internal combustion engine

A piston for an internal combustion engine having two pin bosses provided on a lower surface of a piston head so as to face each other at an interval, a side wall provided on the lower surface of the piston head and disposed on both sides of each of the pin bosses, and a skirt provided continuing to the side wall, a pin hole into which a piston pin can be inserted being formed in each of the two pin bosses, wherein

• inner walls of the side walls and the skirt are continuous with each other, the inner walls are disposed by facing each other on both sides of a pin boss axis with the pin boss axis connecting centers of the two pin holes between them;
• a horizontal section of each of the inner walls is formed along a specific oval shape;
• two through holes are provided in a connecting portion provided between the piston head and the side wall, the two through holes are disposed above an upper end of the skirt at an interval from each other, and the interval is set the same as a width of a lower end of the skirt;
• and
• the two through holes are arranged on respective perpendicular imaginary lines extending from the skirt lower end in the direction perpendicular to the axis of the piston pin.