To reduce a hitting sound and a friction loss caused between a piston and a cylinder inner wall surface, while reducing weight of the piston of a reciprocating internal combustion engine.

Two pairs of rollers R, R, etc. are installed in a piston skirt part 22. The two pairs of rollers R, R, etc. are arranged in a lower position of a piston pin 31 in a side view, and are distributively arranged by pair in a symmetrical position sandwiching the piston pin 31 in a plan view. The respective pairs of rollers R and R are distributively arranged in a symmetrical position for sandwiching a motion reference surface P1 of a connecting rod 32 orthogonal to the piston pin 31. These two pairs of rollers R, R, etc. rollingly contact with the cylinder inner wall surface instead of a piston skirt of a conventional piston, and stabilize a reciprocating motion attitude of a piston 20A.