PURPOSE: To provide a miniaturized and cheap cylinder head for engine, whose internal consumption requirement is small and which can improve fuel consumption.

CONSTITUTION: An inlet rotor 10 is provided at a part of an intake air port 7, and an exhaust rotor 11 is at a part of an exhaust port 8. Through holes 10a and 11a are made in the body section of the both of the rotor 10 and 11. While the inlet rotor 10 is rotating, a through hole 10a is communicated with the intake air port 7, making the intake air port 7 stay in an 'Open' mode, and while the exhaust rotor 11 is rotating, a through hole 11a is communicated with the exhaust air port 8, making the exhaust air port 8 stay in an 'Open' mode. Both rotors 10 and 11 are provided with balance adjusting means 12 and 13. The balance adjusting means 12 and 13 cancel the pressure which works to both rotors 10 and 11 when compression combustion is brought about in a combustion chamber 9, adjusting so as to equalize the pressure applied to both rotors 10 and 11.