An extracorporeal circulation apparatus used for the selective temperature controlling method in which a temperature of an object is kept at a predetermined temperature, includes (A) a fluid replacement supply unit which quantitatively supplies a fluid replacement of which temperature has been adjusted into a blood vessel (B) a blood concentration unit which quantitatively withdraws blood diluted by the fluid replacement from a blood vessel and concentrates the withdrawn diluted blood and (C) a blood supply unit which controls a temperature of the blood which has been concentrated and quantitatively supplies the concentrated blood into a blood vessel, the blood concentration unit comprising a diluted blood temperature sensor which measures a temperature of the withdrawn diluted blood, and the fluid replacement supply unit including a means which controls a temperature of the fluid replacement to be supplied based on a different extent between the measured diluted blood temperature and the predetermined temperature of the object.
