According to one embodiment of the present invention, a forward osmosis-type fresh water composite system includes: a fuel cell device that has a cathode electrode in which carbon dioxide supplied from a plant is converted into carbonate ion (CO 3 2- ) and an anode electrode that produces electric energy by reacting the carbonate ion (CO 3 2- ) with hydrogen and discharges the carbon dioxide; and a carbon dioxide collection unit that reacts the carbon dioxide supplied from the fuel cell device and water supplied from the outside with ammonia separated from a draw solution separation unit so as to produce a high-concentration draw solution and then supplies the high-concentration draw solution to a forward osmosis separation device.