A cylinder head comprises a cylinder head body. The cylinder head body has two intake ports placed on a first side of the cylinder head body with respect to the plug hole, and the two exhaust ports placed on a second side of the cylinder head body with respect to the plug hole. A water jacket of the cylinder head includes: an intake-port-to-intake-port passage portion communicating with the outside of the cylinder head and extending between the two intake ports; an exhaust-port-to-exhaust-port passage portion communicating with the outside of the cylinder head and extending between the two exhaust ports; and a central passage portion communicating with the intake-port-to-intake-port passage portion and the exhaust-port-to-exhaust-port passage portion, the central passage portion being formed so as to surround the plug hole.