The present invention relates to a Stirling engine using rapid gasification of a mixture of water and air which comprises a heat source to rapidly gasify water sprayed to an expansion chamber of a cylinder and rapidly expand internal air. The Stirling engine comprises: a cylinder (10) having a working fluid in an expansion chamber (10a) and a reciprocating piston (11); a connecting rod (21) connected to the piston (11); a crank shaft (20) connected to the connecting rod (21) to convert reciprocating motion of the piston (11) into rotational motion and mounted on a flywheel (22); and a heat source (30) to heat the working fluid. The cylinder (10) has a bottom unit which comes in contact with the expansion chamber (10a) below a bottom dead center of the piston (11) and consists of an insulation unit (12). A plurality of water spray ports (42) are formed on a wall of the cylinder (10) which comes in contact with the expansion chamber (10a). One end of a water spray nozzle (43) is connected to a water tank (41), and the water spray nozzle (43) is installed on the water spray ports (42). Water periodically sprayed to the expansion chamber (10a) of the cylinder (10) through the water spray nozzle (43) is rapidly gasified by heat transferred through the insulation unit (12) and rapidly expanded with air which is the working fluid of the expansion chamber (10a) of the cylinder (10) to move the piston (11) forwards. The piston (11) reciprocates by rapid vaporization (gasification) of a mixture of the water and the air in the expansion chamber of the cylinder to obtain motion energy for rotating the crank shaft.
