An integrated flow control valve apparatus for controlling a flow rate of coolant in an engine cooling system for cooling an engine including a cylinder block and a cylinder head mounted above the cylinder block, includes a valve housing; a plurality of coolant ports formed at the valve housing and provided as inlets and outlets through which the coolant flows into and out of the valve housing; and valves configured for opening and closing the coolant ports, wherein the coolant ports include a first inlet port for introduction of the coolant from the cylinder block and a second inlet port for introduction of the coolant from the cylinder head into the valve housing; and the flow of the coolant at the first and second inlet ports is controlled by the valves configured to vary the flow of the coolant in the cylinder block and the cylinder head.