A gas solution manufacturing device 1 includes a gas supply line 2 configured to supply a gas as a raw material of a gas solution, a liquid supply line 3 configured to supply a liquid as a raw material of the gas solution, a gas solution production unit 4 configured to mix the gas and the liquid together to produce the gas solution, a gas-liquid separation unit 5 configured to perform gas-liquid separation of the produced gas solution into a supplied liquid to be supplied to a use point and a discharged gas to be discharged through an exhaust port, and a gas dissolving unit 6 provided in the liquid supply line 4 and configured to dissolve the discharged gas resulting from the gas-liquid separation in the liquid. The gas dissolving unit 6 is configured with a hollow fiber membrane configured with a gas permeable membrane.