According to the present invention, there is provided a cylinder head for a multi-cylinder internal combustion engine, comprising: a bottom wall having an upper face which defines a waterjacket, the bottom wall having spaced recessed wall portions which have lower faces defining upper spaces of adjacent combustion chambers, the bottom wall having a bottom wall portion formed between the recessed wall portions to divide the upper spaces of the adjacent combustion chambers; and slit means formed on the upper face of the bottom wall portion and extending within the bottom wall portion toward a lower face of the bottom wall portion.