A measurement cell (40a) is formed so as to extend in a direction along which a centrifugal force is applied, and a capillary area (47a) to which a sample liquid is sucked by a capillary force is formed on one of the side walls of the measurement cell (40a), the side walls being arranged in a rotational direction. The capillary area (47a) extends from the outer periphery position to the inner periphery of the measurement cell (40a), thereby reducing the size of an analyzing device. Further, the sample liquid in the measurement cell (40a) is sucked to the capillary area (47a) by slowing or stopping a rotation, and then the rotation is accelerated to return the sample liquid in the capillary area (47a) to the measurement cell (40a). It is therefore possible to achieve a sufficient agitating effect and conduct measurement with a small quantity of sample liquid.