Electrochemical separation of carbon dioxide from simulated flue gas was investigated using an anion exchange membrane. Carbon dioxide reacts with hydroxide ions to produce hydrogen carbonate and carbonate ions at the cathode. These ions migrate to the anode, where they are converted to carbon dioxide gas and oxygen. Extensive experiments under various conditions of anode humidification and electrode composition demonstrated the possibility of the separation. Transport numbers of hydrogen carbonate and carbonate ions were obtained. The voltage required for separation was around 2.0 V/cell, the reduction of which remains to be solved.