To facilitate assembling, reduce an output loss, permit the restriction of damage on the surface of a sliding section, provide a stabilized high performance, realize the elongation of a life and, further, eliminate the gas bearing pad or the orifice of the sliding section, simplify the parts, and reduce the cost as well as the input of an external power, in the structure of sliding section for Stirling engine or the like.

The configurations 2a of end parts of sectional surfaces of sliding parts or parts engaged with the sliding parts are provided with a curvature while the configurations 2a of ends of sectional surfaces of a piston 1, a piston side cylinder 3, a displacer 4, a displacer side cylinder 5, a displacer rod 6 and a piston hole 7 are provided respectively with the same curvature.