There is provided an engine water-cooling device that can increase warming-up efficiency of an engine. The engine water-cooling device includes a thermostat housing 2 that houses a thermostat 1. The thermostat housing 2 is mounted to a front wall 5a of a cylinder head 5 in one side portion in a width direction of the cylinder head 5. A cooling water pump 3 is mounted to a front wall 6c of a cylinder block 6 in a central portion in a width direction of the cylinder block 6. A bypass passage 4 includes an intra-head bypass passage 4a in the cylinder head 5, and the intra-head bypass passage 4a includes a width-direction passage portion 4c extending from a position behind the thermostat housing 2 to a position behind and above the cooling water pump 3.
