Abstract: A cooling water path for an internal combustion engine characterized in that within a water jacket in the cylinder head there are installed a plurality of head partition walls located between adjacent cylinders extending the full width of the head with a ventilation hole provided at the top. Within a water jacket in the cylinder block there are installed a No. 1 block partition wall extending in the longitudinal direction of the block between adjacent cylinders as well as No. 2 block partition walls extending in the width direction of the block between adjacent cylinders or lateral to the cylinder center, said head water jacket and said block water jacket vertically communicating with each other.