In a cell analyze apparatus, a light beam is irradiated onto cells (or particles like the cells) flowing through a flow cell so as to measure cell light information for each cell with respect to a plurality of parameters (for example, the forward scattered light intensity, the right angle scattered light intensity and the intensity of fluorescence by different dye). Based on a minimal point of a histogram associated with the cell light information with respect to one or more parameters, the cell population is subdivided into fractions. When the minimal point is missing in the histogram, the parameters above are converted by use of a predetermined conversion expression (for example, a coordinate conversion is effected on the parameters) such that a minimal point is detected from the histogram of cell light information related to the new parameters obtained by the conversion, thereby subdividing an objective cell population.