A Stirling engine comprising: - a crank case with a crank shaft arranged therein, - a displacer cylinder with a reciprocatingly arranged displacer piston therein, said displacer piston being connected to said crank shaft via a connecting rod extending through a first end of said displacer cylinder, and wherein the displacer cylinder defines a hot chamber and a cool chamber separated by the displacer piston, - a working cylinder defining a working cylinder chamber with a reciprocatingly arranged working piston therein, said working piston being connected to said crank shaft via a connecting rod extending through a first end of the working cylinder, - a heater device, arranged at a second end of said displacer cylinder opposite to said first end and configured to heat a working gas which is present in the hot chamber of the displacer cylinder and in fluid communication with the working cylinder chamber through a working gas channel which comprises - a first heat exchanger extending from a cylinder head of the displacer cylinder into the heater device, - a second heat exchanger formed by a regenerator arranged outside the heater device, and - a transition flow element provided between said second heat exchanger and the working cylinder, - wherein the Stirling engine also comprises a cooling system for cooling of the displacer cylinder, the working cylinder and the tubular transition flow element said Stirling engine being characterised in that it comprises a first outer tube arranged outside and enclosing the working cylinder, and that the cooling system comprises a first channel configured to receive a cooling fluid and defined by the outer periphery of the working cylinder and the inner periphery of said first outer tube, and that said channel covers at least 50% of the outer peripheral surface of the working cylinder. - a crank case with a crank shaft arranged therein, - a displacer cylinder with a reciprocatingly arranged displacer piston therein, said displacer piston being connected to said crank shaft via a connecting rod extending through a first end of said displacer cylinder, and wherein the displacer cylinder defines a hot chamber and a cool chamber separated by the displacer piston, - a working cylinder defining a working cylinder chamber with a reciprocatingly arranged working piston therein, said working piston being connected to said crank shaft via a connecting rod extending through a first end of the working cylinder, - a heater device, arranged at a second end of said displacer cylinder opposite to said first end and configured to heat a working gas which is present in the hot chamber of the displacer cylinder and in fluid communication with the working cylinder chamber through a working gas channel which comprises - a first heat exchanger extending from a cylinder head of the displacer cylinder into the heater device, - a second heat exchanger formed by a regenerator arranged outside the heater device, and - a transition flow element provided between said second heat exchanger and the working cylinder, - wherein the Stirling engine also comprises a cooling system for cooling of the displacer cylinder, the working cylinder and the tubular transition flow element said Stirling engine being characterised in that it comprises a first outer tube arranged outside and enclosing the working cylinder, and that the cooling system comprises a first channel configured to receive a cooling fluid and defined by the outer periphery of the working cylinder and the inner periphery of said first outer tube, and that said channel covers at least 50% of the outer peripheral surface of the working cylinder.