Abstract: The present invention aims to shorten an aspiration time, when aspirating a red blood cell component of a liquid sample having high viscosity. When aspirating the red blood cell component of a blood sample through a nozzle tip, a piston is pulled at its maximum to produce a maximum aspirating force, and starts aspiration. When a pressure in an aspirating system becomes equal to a predetermined value .alpha., the piston is returned to a position in which only a necessary aspiration volume of the liquid sample can be aspirated. Since the maximum aspirating force of the pump is utilized during the aspiration, the aspirating operation can be carried out more quickly.

Abstract: In pipetting a blood plasma component and a red blood cell component separated vertically in a blood sample by a centrifugation, the red blood cell component having a high viscosity is aspirated as quickly as possible. A nozzle 32 is composed of a nozzle base 35 and a disposable tip 36, and is transferred upwardly and downwardly and to the right and left by an XYZ robot 34. At first the blood plasma component in the blood sample put in a test tube 62 is pipetted by a nozzle 32, and then an inner wall of the disposable tip 36 is coated with the blood plasma component, and thereafter the red blood component is pipetted.