NOVELTY - A carbon-dioxide separation apparatus has carbon dioxide facilitated-transport membrane (10) obtained by adding 2,3-diaminopropionic acid to polyvinyl alcohol polyacrylic-acid copolymer gel membrane, and pressure regulation unit (15). Source gas (FG) having carbon dioxide and steam is fed to raw material side of membrane (10) at 100degrees C or more. Unit (15) adjusts entire pressure of source gas to a pressure, which is more than minimum steam saturation pressure and less than pressure at which steam saturation is set as 1.    USE - Apparatus is used for separating carbon dioxide from source gas (claimed) such as hydrogen-containing reformed gas used for fuel cell.    ADVANTAGE - The carbon-dioxide separation apparatus efficiently separates carbon dioxide from source gas using carbon-dioxide facilitated-transport membrane, which exhibits favorable film-property ability on high temperature and pressure conditions.    DETAILED DESCRIPTION - A carbon-dioxide separation apparatus has a carbon dioxide facilitated-transport membrane (10), which is obtained by adding 2,3-diaminopropionic acid to polyvinyl alcohol polyacrylic-acid copolymer gel membrane, and a pressure regulation unit (15). Source gas (FG) with which carbon dioxide and steam are contained in predetermined main-component gas, is supplied to raw material side of the transport membrane at supply temperature of 100degrees C or more. Carbon dioxide, which permeated through the transport membrane, is removed from permeation side. The unit (15) adjusts the entire pressure of source gas supplied to the transport membrane, to a pressure (P) which is more than pressure (P1) and less than pressure (P2). The pressure (P1) is a pressure at which steam saturation prescribed by ratio obtained by dividing steam partial pressure in source gas with saturated steam pressure determined at supply temperature, becomes minimum saturation set within the range of 0.3-0.6. The pressure (P2) is a pressure at which steam saturation is set to 1.    DESCRIPTION OF DRAWING(S) - The drawing shows the schematic block diagram of carbon-dioxide separation apparatus. (Drawing includes non-English language text)    Carbon-dioxide facilitated-transport membrane (10)    Pressure regulation unit (15)    Carbon-monoxide transformer (20)    Sweep gas path (21)    Source gas (FG)