PURPOSE: To smoothen sucked gas flow and to improve degree of freedom in a layout by forming a sucking gas passage communicated with a gas sucking port of a combustion chamber in a cylinder head for an engine along a spiral axis having the fixed curvature.

CONSTITUTION: A head cover and a cylinder block are joined on upper face 2 and on lower face 3 respectively in the cylinder head 1 composed of Al alloy and formed with die casting and the combustion chamber 4 is arranged as recessed state at the lower face thereof. The gas sucking port 5 and gas exhaust port 6 are parallelly arranged at the roof part of this combustion chamber 4 and communicated with the gas sucking passage 12 and gas exhaust passage 13, respectively. In the cylinder head 1 for the above engine, the above gas sucking passage 12 is formed so as to make the spiral state having the fixed curvature. By this method, the gas suction is smoothened as spiral-state and also the degree of freedom in the layout of bolt hole 9, bush rod inserting hole 10, cold blast passage 15, etc., around the gas sucking passage 12 is improved. The gas sucking passage 12 can be easily formed by using a metallic mold 21 where the spiral core 23 for forming this is made freely rotatable around center axis C to a master mold 22.