A Stirling engine A has a pressure container 1 filled with a working gas, a cylinder 2 secured inside the pressure container 1, a power piston 3 provided inside the cylinder 2, and a displacer 4a provided inside the cylinder 2 on the same axis as the power piston 3. The displacer 4 has a displacer piston 41a that slides inside the cylinder 2, and a rod 42a which is connected and fixed to the displacer piston 41a and placed through a slide hole 31 formed at the center of the power piston 3. The rod 42a is formed in the shape of a hollow pipe.