Abstract: A method of automatically distinguishing absorption or non-absorption of whole blood or blood plasma by using a reflective photosensor in an automatic immunoassay device including a round cartridge which may simultaneously perform the centrifugation and automatic analysis of a blood sample and a tip which may be moved up, down, left and right based on the round cartridge, the method includes: installing the reflective photosensor below the round cartridge; mounting the tip above the round cartridge, and continuously measuring blood non-absorption data in a range including a position where the blood is absorbed by using the reflective photosensor, collecting the measured data and storing the collected data while the tip is raised; continuously measuring blood absorption data by using the reflective photosensor while the tip is lowered and absorbs the blood present in the range including the position where the blood is absorbed from the round cartridge; and determining whether a type of the blood is whole blood