A carbon dioxide separation method including the steps of: feeding a mixed gas that contains at least carbon dioxide and water vapor to a carbon dioxide separation membrane that contains a hydrophilic resin and a carbon dioxide carrier; separating, from the mixed gas, a permeation gas that contains the carbon dioxide by use of the carbon dioxide separation membrane; adjusting temperature of gas which contacts the carbon dioxide separation membrane so that a temperature difference between the mixed gas and the permeation gas is not lower than 0° C. and not higher than 20° C.; and adjusting pressure of the permeation gas, the pressure of the permeation gas and water vapor partial pressure in the mixed gas satisfying the following formula (1): 2.5 kPaA