A piston for an engine comprising: a skirt part; and a plurality of resin coating films formed on a surface of the skirt part, wherein the plurality of resin coating films are arranged in a plurality of discrete spots on the surface of the skirt part, and a mesh-like groove is formed by a recess defined by each of the plurality of the resin coating films adjacent to each other and the surface of the skirt part between the resin coating films, wherein the plurality of resin coating films are arranged at a predetermined interval in a piston circumference direction of the skirt part forming a plurality of resin coating film rows, such that each of the resin coating film rows adjacent to each other in a piston moving direction is arranged by shifting the resin coating film rows with respect to each other in the piston circumference direction, and wherein the recess formed on the skirt part between the resin coating films adjacent to each other in a piston circumference direction in a first resin coating film row has end openings (7a, 7b), each of which is set to face a resin coating film in a second resin coating film row adjacent to the first resin coating film row in a piston moving direction, characterised in that both end parts of each of the resin coating films in the piston moving direction are formed in a concave shape when seen in a piston radius direction, such that a lubricant which has moved along the recess by inertia in accordance with a piston movement collides against the concave end part of the resin coating film in the second resin coating film row, and, due to an angle of the concave shape, the lubricant does not move away in the piston circumference direction, but tends to return to the original recess by a bounce back movement. a skirt part; and a plurality of resin coating films formed on a surface of the skirt part, wherein the plurality of resin coating films are arranged in a plurality of discrete spots on the surface of the skirt part, and a mesh-like groove is formed by a recess defined by each of the plurality of the resin coating films adjacent to each other and the surface of the skirt part between the resin coating films, wherein the plurality of resin coating films are arranged at a predetermined interval in a piston circumference direction of the skirt part forming a plurality of resin coating film rows, such that each of the resin coating film rows adjacent to each other in a piston moving direction is arranged by shifting the resin coating film rows with respect to each other in the piston circumference direction, and wherein the recess formed on the skirt part between the resin coating films adjacent to each other in a piston circumference direction in a first resin coating film row has end openings (7a, 7b), each of which is set to face a resin coating film in a second resin coating film row adjacent to the first resin coating film row in a piston moving direction, characterised in that both end parts of each of the resin coating films in the piston moving direction are formed in a concave shape when seen in a piston radius direction, such that a lubricant which has moved along the recess by inertia in accordance with a piston movement collides against the concave end part of the resin coating film in the second resin coating film row, and, due to an angle of the concave shape, the lubricant does not move away in the piston circumference direction, but tends to return to the original recess by a bounce back movement.