To take out energy of the same degree or more of energy by a conventional internal combustion engine, without causing the problem caused by fuel resources.

This prime mover is composed of a housing 101 formed in a sealed form, an inner chamber 103 formed in a cross-sectional circular shape in the housing 101, and a rotor 115 arranged in the inner chamber 103 so as to be rotatable around a rotor shaft 116. When rotating the rotor 115, the inner chamber 103 is partitioned and formed into a primary operation chamber 121 and a secondary operation chamber 122. An air supply port 117 and an exhaust port 119 are oppositely arranged in the housing 101, and a freely openable-closable intake valve 125 is arranged for opening and closing the air supply port 117. Carbon dioxide gas 35a of a high pressure state is exposed under atmospheric pressure of one atmospheric pressure when supplied in the primary operation chamber 121, and expands its volume at once, and rotates the rotor 115 by this force.