PURPOSE: To improve an operation efficiency by controlling closing and opening of intake and discharge valves based on an engine operation condition, and variably controlling a variable cycle engine to 2/4 cycle, in a variable cycle engine provided with the intake and exhaust valves which are opened and closed by an electromagnetic power.
CONSTITUTION: At an opening part toward a combustion chamber 13 of intake and exhaust pipes 2, 3 connected to the chamber 13 of an engine 1, intake and exhaust valves 21, 31 are provided to be openly and closely driven by an energizing control to exhaust valve lifters 22, 32 formed of an electromagnetic solenoid. In the combustion chamber 13, primary and secondary nozzles 51, 52 are mounted, and injection timing of the nozzles 51, 52 is controlled in response to 2/4 cycle. The fuel injection timing or opening/closing timing of intake and exhaust valve lifters 22, 32 are variable controlled by a controller 4 which inputs output signals of a rotation sensor 14, a boost pressure sensor 23 and an acceleration sensor 61, and an engine operation condition is changed to two or four cycle operations.