PURPOSE: To provide a compressor having a high capacity although its structure is rather small, by disposing a cylinder unit for a steam engine and a cylinder unit for a compressor coaxially in the manner of opposing each other, and connecting them together at the central portion by the intermediary of a rotatable swash plate shaped in a symmetrical form.

CONSTITUTION: Driving cylinders 2 of a cylinder unit 25 for a steam engine and compression cylinders 3 of a cylinder unit 26 for a compressor are disposed coaxially in an evacuated casing 1 in the manner of opposing each other. Pistons 9, 18 are fitted respectively in the cylinders 2, 3 in a freely slidable manner, and connecting rods 10, 17 of the pistons 9, 18 are connected to oscillating plates 12, 15 by means of ball joints 11, 16, which oscillating plates are supported by a rotatable swash plate 4 shaped in a symmetrical form and disposed at the central portion in the casing 1, in a freely rotatable manner by means of bearings 5. With such an arrangement, the unit 25 is driven by high-pressure gas (steam or the like) introduced from an intake pipe 6 and discharged from an exhaust pipe 8, and the unit 26 is driven by the driving force of the unit 25 by the intermediary of the rotatable swash plate 4.