Disclosed is a gas-liquid separating device comprising: a main body in which an internal space is formed, and an injecting hole and a discharging hole which reach the internal space are formed; an electric osmosis material housed inside the internal space, and delimits the internal space into a first and a second region, the first region being reached by the injecting hole and the discharging hole; a first electrode joined to the electric osmosis material on a first region side; and a second electrode joined to the electric osmosis material on a second region side, wherein gas including moisture vapor is injected to the first region from the injecting hole, water obtained by condensing the moisture vapor in the first region electrically osmosis through the electric osmosis material from the first region to the second region by applying voltage in between the first and the second electrode.