A mist-containing gas analysis device that measures a concentration of a measurement-target substance, which can be an amine or ammonia, in a combustion exhaust target gas, from which carbon dioxide is absorbed and removed by an amine-containing absorbing liquid, and which contains a mist of the measurement-target substance flowing through a duct, the device comprising: pressure measuring means for measuring a pressure of the target gas that flows through the duct; temperature measuring means for measuring a temperature of the target gas that flows through the duct; flow rate measuring means for measuring a flow rate of the target gas that flows through the duct by using a radio wave or an ultrasonic wave; water content measuring means for measuring water content in the target gas that flows through the duct by using infrared light; a collection container that contains the amine-containing absorbing liquid which dissolves the measurement-target substance; target gas sampling means (101,102,104,111,112,114,115,116,121,123,124,125,126) for absorbing the target gas by using suction means and for sampling the target gas; target gas feeding means (102,104,114,115,121,122,123,124,125,126) for feeding the target gas sampled by the target gas sampling means into the amine-containing absorbing liquid in the collection container; suction flow rate control means for controlling the suction means in such a manner that a suction velocity of the target gas being suctioned by the suction means is within a predetermined ratio with respect to a target gas flow velocity calculated based on the pressure of the target gas measured by the pressure measuring means, the temperature of the target gas measured by the temperature measuring means, the flow rate of the target gas measured by the flow rate measuring means, and the water content of the target gas measured by the water content measuring means; liquid aliquot taking means (105,127,128,129) for taking an aliquot of the liquid in the collection container; and measuring means for measuring the concentration of the measurement-target substance in the aliquot of the liquid taken by the liquid aliquot taking means. pressure measuring means for measuring a pressure of the target gas that flows through the duct; temperature measuring means for measuring a temperature of the target gas that flows through the duct; flow rate measuring means for measuring a flow rate of the target gas that flows through the duct by using a radio wave or an ultrasonic wave; water content measuring means for measuring water content in the target gas that flows through the duct by using infrared light; a collection container that contains the amine-containing absorbing liquid which dissolves the measurement-target substance; target gas sampling means (101,102,104,111,112,114,115,116,121,123,124,125,126) for absorbing the target gas by using suction means and for sampling the target gas; target gas feeding means (102,104,114,115,121,122,123,124,125,126) for feeding the target gas sampled by the target gas sampling means into the amine-containing absorbing liquid in the collection container; suction flow rate control means for controlling the suction means in such a manner that a suction velocity of the target gas being suctioned by the suction means is within a predetermined ratio with respect to a target gas flow velocity calculated based on the pressure of the target gas measured by the pressure measuring means, the temperature of the target gas measured by the temperature measuring means, the flow rate of the target gas measured by the flow rate measuring means, and the water content of the target gas measured by the water content measuring means; liquid aliquot taking means (105,127,128,129) for taking an aliquot of the liquid in the collection container; and measuring means for measuring the concentration of the measurement-target substance in the aliquot of the liquid taken by the liquid aliquot taking means.