To sufficiently cool the periphery of a combustion chamber of a cylinder head, and to improve the output and the fuel consumption.

This cooling system for an engine is provided with a block-side water jacket mounted on a cylinder block of an engine, a head-side water jacket mounted on the cylinder head, a water pump mounted on the cylinder block, a radiator inlet passage for guiding the coolant having passed through the head-side water jacket to a radiator, and a radiator outlet passage for guiding the cooling water cooled by the radiator to a water pump. A cooling water passage for the head is provided with one end side communicated with a discharge side of the water pump and the other end side communicated with the head-side water jacket.