Piston gas lubrication structure and Stirling engines

Gas lubrication structure 1A includes a high-temperature side cylinder 22, and the expansion piston 21A which gas lubrication is performed between the high temperature side cylinder 22, provided on the outer circumferential surface of the expansion piston 21A, the linear expansion than the base material of the expansion piston 21A rate is high, and a layer 60 formed by and flexible resistant material. The thickness of the normal temperature of the layer 60 has a clearance of size or larger which is formed between the layer 60 and the high-temperature side cylinder 22. The thickness of the normal temperature of the layer 60, even when thermal expansion occurs in use conditions, has become capable of forming a clearance thickness between the layer 60 and the high-temperature side cylinder 22.