To provide a cylinder head for suppressing the generation of steam bubbles inside a cooling water passage so as to effectively discharge the steam bubbles, a manufacturing method of the cylinder head, and a casting core for use in the manufacture.

In a cylinder head for a multiple cylinder internal combustion engine provided with an intake/exhaust passage, a valve guide and a bolt hole for a cylinder, there are provided a deck face, a valve drive space, two side faces and two end faces. A vertical cooling water passage 24 extends along the cylinder and comprises a cooling water inlet opening and a cooling water outlet opening 29 connected to the cooling water passage inside a cylinder block. There is provided at least one lateral cooling water passage 27 for deaeration and steam bubble discharge. The cooling water passage 21 extends laterally along a plurality of cylinders inside an intermediate wall 21 above the vertical cooling water passage, is connected at one end thereof near the side face to the vertical cooling water passage via a communication opening 32, and is provided with a discharging device at the other end thereof facing the communication opening.