Abstract: A piston in which a solid lubricant resin layer made of a resin containing a solid lubricant is formed at a skirt portion. A guide groove absent area where no guide groove is formed, which is provided in a predetermined range of the solid lubricant resin layer at a center portion in a width direction. The guide grooves directing from the both ends in the width direction of the guide groove absent area to both ends in the width direction of the skirt portion. The end portions of the guide grooves extended to end edges of the solid lubricant resin layer to form open ends. The solid lubricant resin layer and the guide grooves are formed at least at a thrust side skirt portion. The guide grooves are formed in a shape inclined upward from the guide groove absent area toward the end edges of the solid lubricant resin layer.

Abstract: A piston in which a solid lubricant resin layer made of a resin containing a solid lubricant is formed at a skirt portion. A guide groove absent area where no guide groove is formed, which is provided in a predetermined range of the solid lubricant resin layer at a center portion in a width direction. The guide grooves directing from the both ends in the width direction of the guide groove absent area to both ends in the width direction of the skirt portion. The end portions of the guide grooves extended to end edges of the solid lubricant resin layer to form open ends. The solid lubricant resin layer and the guide grooves are formed at least at a thrust side skirt portion. The guide grooves are formed in a shape inclined upward from the guide groove absent area toward the end edges of the solid lubricant resin layer.