Cylinder head and engine

A cylinder head comprising:

• a lower deck;
• an upper deck that is provided above the lower deck so as to face the lower deck and that defines a cooling water flow space between the lower deck and the upper deck;
• a wall portion that is formed between the lower deck and the upper deck and includes a valve-hole forming wall forming an intake valve hole and an exhaust valve hole which are opened into a lower surface of the lower deck,
• wherein the lower deck includes:
• a cooling water introduction hole that passes through the lower deck in a vertical direction so as to extend in a circumferential direction of a virtual circle surrounding the valve-hole forming wall when seen from a plan view;
• and
• a rib that is provided to be arranged in the circumferential direction of the virtual circle with respect to the cooling water introduction hole and projects from an upper surface of the lower deck so as to extend in the circumferential direction.