PURPOSE: To provide a reciprocative engine which achieves combustion efficiency with the output of similar magnitude to a gas turbine engine.

CONSTITUTION: An engine concerned is equipped with a periodic mechanism for enhancement of the combustion efficiency, wherein any piston or the like is omitted for shortening the combustion period. Valve having an effect of opening and closing with rotating are furnished in front of and behind the combustion chamber 1 which is divided radially, and one of them is used as a suction valve 2 while the other used as an exhaust valve 3. A turbine 4 is installed in front of the exhaust valve 3 so as to generate a torque, and with which a compressor 5 installed in front of the suction valve 2 and the suction and exhaust valves 2, 3 are driven.