A carbon dioxide separating and capturing apparatus comprising: an absorption tower to which a gas containing carbon dioxide is introduced, the absorption tower being configured to allow the gas to contact with an absorption liquid for absorbing the carbon dioxide, and to discharge a rich liquid which is the absorption liquid having absorbed the carbon dioxide; a regeneration tower configured to heat the absorption liquid to cause the absorption liquid to release a gas containing the carbon dioxide, and to discharge a lean liquid whose concentration of dissolved carbon dioxide is lower than a concentration of dissolved carbon dioxide in the rich liquid; and first and second regenerative heat exchangers (5, 21) configured to heat the rich liquid by using the lean liquid, wherein the first regenerative heat exchanger is a heat exchanger of plate type, heats the rich liquid discharged from the absorption tower by using the lean liquid discharged from the second regenerative heat exchanger, and discharges the rich liquid in a liquid phase, the second regenerative heat exchanger is a heat exchanger of shell-and-tube type, heats the rich liquid in the liquid phase discharged from the first regenerative heat exchanger by using the lean liquid discharged from the regeneration tower, and causes the rich liquid to generate a steam and to release a carbon dioxide gas, the lean liquid discharged from the first regenerative heat exchanger is fed to the absorption tower, and the rich liquid, the steam and the carbon dioxide gas discharged from the second regenerative heat exchanger is fed to the regeneration tower, the apparatus further comprising: a first measuring device configured to measure the concentration of the dissolved carbon dioxide in the rich liquid fed to the first regenerative heat exchanger; a second measuring device configured to measure a temperature of the rich liquid discharged from the first regenerative heat exchanger; a third measuring device configured to measure a pressure of the rich liquid discharged from the first regenerative heat exchanger; a pressure adjusting valve configured to adjust the pressure of the rich liquid discharged from the first regenerative heat exchanger; and a controller configured to calculate, by using the values of the first and second measuring devices and gas-liquid equilibrium data of the absorption liquid, a pressure value at which the rich liquid discharged from the first regenerative heat exchanger maintains it in the liquid phase, and to control the pressure adjusting valve so that a measurement result of the third measuring device is equal to or greater than the calculated pressure value. an absorption tower to which a gas containing carbon dioxide is introduced, the absorption tower being configured to allow the gas to contact with an absorption liquid for absorbing the carbon dioxide, and to discharge a rich liquid which is the absorption liquid having absorbed the carbon dioxide; a regeneration tower configured to heat the absorption liquid to cause the absorption liquid to release a gas containing the carbon dioxide, and to discharge a lean liquid whose concentration of dissolved carbon dioxide is lower than a concentration of dissolved carbon dioxide in the rich liquid; and first and second regenerative heat exchangers (5, 21) configured to heat the rich liquid by using the lean liquid, wherein the first regenerative heat exchanger is a heat exchanger of plate type, heats the rich liquid discharged from the absorption tower by using the lean liquid discharged from the second regenerative heat exchanger, and discharges the rich liquid in a liquid phase, the second regenerative heat exchanger is a heat exchanger of shell-and-tube type, heats the rich liquid in the liquid phase discharged from the first regenerative heat exchanger by using the lean liquid discharged from the regeneration tower, and causes the rich liquid to generate a steam and to release a carbon dioxide gas, the lean liquid discharged from the first regenerative heat exchanger is fed to the absorption tower, and the rich liquid, the steam and the carbon dioxide gas discharged from the second regenerative heat exchanger is fed to the regeneration tower, a first measuring device configured to measure the concentration of the dissolved carbon dioxide in the rich liquid fed to the first regenerative heat exchanger; a second measuring device configured to measure a temperature of the rich liquid discharged from the first regenerative heat exchanger; a third measuring device configured to measure a pressure of the rich liquid discharged from the first regenerative heat exchanger; a pressure adjusting valve configured to adjust the pressure of the rich liquid discharged from the first regenerative heat exchanger; and a controller configured to calculate, by using the values of the first and second measuring devices and gas-liquid equilibrium data of the absorption liquid, a pressure value at which the rich liquid discharged from the first regenerative heat exchanger maintains it in the liquid phase, and to control the pressure adjusting valve so that a measurement result of the third measuring device is equal to or greater than the calculated pressure value.