A first coolant flow passage (31, 32) is provided to extend in a longitudinal direction of a cylinder head (101). In at least one of cross sections perpendicular to the longitudinal direction, the first coolant flow passage (31, 32) is located between a flat plane (S1) including central axes of a plurality of combustion chambers (4) and parallel to the longitudinal direction and a central line plane (S2) including central lines of a plurality of intake ports (2). In at least one of cross sections perpendicular to the longitudinal direction, at least a portion (20c) of a second coolant flow passage is located between a cylinder block mating surface (la) of the cylinder head (101) and the intake port central line plane (S2). A coolant at a temperature lower than that of a coolant flowing in the second coolant flow passage (20c) flows in the first coolant flow passage (31, 32).