A method for detecting liquid overflowing from at least one of a plurality of containers comprised in an analyzer, each container containing liquid, the method comprising the steps of: for each one of one or more containers among the plurality of containers, during a washing step, measuring an absorbance of the liquid contained in the one container at a plurality of spatially separated regions of the one container at a first time corresponding to the one container; calculating a standard deviation of the absorbance of the liquid measured at the plurality of spatially separated regions of the one container at the first time corresponding to the one container, as a first standard deviation; during a washing step, measuring an absorbance of the liquid contained in the one container at a plurality of spatially separated regions of the one container at a second time corresponding to the one container; calculating a standard deviation of the absorbance of the liquid measured at the plurality of spatially separated regions of the one container at the second time corresponding to the one container, as a second standard deviation; and comparing a difference between the first standard deviation and the second standard deviation, with a predetermined threshold value; and judging that the liquid is overflowing from at least one of the plurality of containers if the difference between the first standard deviation and the second standard deviation is greater than the predetermined threshold value in the step of comparing for all of the one or more containers among the plurality of containers. for each one of one or more containers among the plurality of containers, during a washing step, measuring an absorbance of the liquid contained in the one container at a plurality of spatially separated regions of the one container at a first time corresponding to the one container; calculating a standard deviation of the absorbance of the liquid measured at the plurality of spatially separated regions of the one container at the first time corresponding to the one container, as a first standard deviation; during a washing step, measuring an absorbance of the liquid contained in the one container at a plurality of spatially separated regions of the one container at a second time corresponding to the one container; calculating a standard deviation of the absorbance of the liquid measured at the plurality of spatially separated regions of the one container at the second time corresponding to the one container, as a second standard deviation; and comparing a difference between the first standard deviation and the second standard deviation, with a predetermined threshold value; and during a washing step, measuring an absorbance of the liquid contained in the one container at a plurality of spatially separated regions of the one container at a first time corresponding to the one container; calculating a standard deviation of the absorbance of the liquid measured at the plurality of spatially separated regions of the one container at the first time corresponding to the one container, as a first standard deviation; during a washing step, measuring an absorbance of the liquid contained in the one container at a plurality of spatially separated regions of the one container at a second time corresponding to the one container; calculating a standard deviation of the absorbance of the liquid measured at the plurality of spatially separated regions of the one container at the second time corresponding to the one container, as a second standard deviation; and comparing a difference between the first standard deviation and the second standard deviation, with a predetermined threshold value; and judging that the liquid is overflowing from at least one of the plurality of containers if the difference between the first standard deviation and the second standard deviation is greater than the predetermined threshold value in the step of comparing for all of the one or more containers among the plurality of containers.