A system for analyzing a CO2 concentration of an amine-based absorbing solution includes a measurement apparatus that measures a viscosity of the amine-based absorbing solution and at least one selected from conductivity and ultrasonic propagation velocity of the amine-based absorbing solution, wherein the amine-based absorbing solution absorbs and removes CO2 from a target gas by gas-liquid contact with the target gas; and a controller that determines the CO2 concentration of the amine-based absorbing solution from results measured by the measurement apparatus.