A blood analyzer comprising: a sample preparation portion configured to prepare a first measurement sample containing a blood sample, a hemolytic agent and a diluting solution, and a second measurement sample containing said blood sample, the same hemolytic agent as said hemolytic agent, a staining agent, and the same diluting solution as said diluting solution; a light information generation portion configured to generate first fluorescent information and at least two types of first scattered light information from said first measurement sample and to generate second fluorescent information and second scattered light information from said second measurement sample; and a control portion configured to perform a first classification of white blood cells in said first measurement sample into at least four groups of monocytes, neutrophils, eosinophils and a group of the others on the basis of said first fluorescent information and said two types of first scattered light information generated by said light information generation portion and to classify blood cells in said second measurement sample into malaria-infected red blood cells and a group of the others on the basis of said second fluorescent information and said second scattered light information generated by said light information generation portion; wherein said sample preparation portion is configured to prepare said first measurement sample by mixing said blood sample, said hemolytic agent stored in a predetermined reagent container and a predetermined quantity of diluting solution and prepare said second measurement sample by mixing said blood sample, said hemolytic agent stored in said predetermined reagent container and a quantity of said diluting solution smaller than said predetermined quantity of diluting solution for the first measurement sample, such that said dilution magnification of said hemolytic agent in said second measurement sample is smaller than said dilution magnification of said hemolytic agent in said first measurement sample, and wherein the staining agent includes a DNA-selective fluorescent dye. a sample preparation portion configured to prepare a first measurement sample containing a blood sample, a hemolytic agent and a diluting solution, and a second measurement sample containing said blood sample, the same hemolytic agent as said hemolytic agent, a staining agent, and the same diluting solution as said diluting solution; a light information generation portion configured to generate first fluorescent information and at least two types of first scattered light information from said first measurement sample and to generate second fluorescent information and second scattered light information from said second measurement sample; and a control portion configured to perform a first classification of white blood cells in said first measurement sample into at least four groups of monocytes, neutrophils, eosinophils and a group of the others on the basis of said first fluorescent information and said two types of first scattered light information generated by said light information generation portion and to classify blood cells in said second measurement sample into malaria-infected red blood cells and a group of the others on the basis of said second fluorescent information and said second scattered light information generated by said light information generation portion; wherein said sample preparation portion is configured to prepare said first measurement sample by mixing said blood sample, said hemolytic agent stored in a predetermined reagent container and a predetermined quantity of diluting solution and prepare said second measurement sample by mixing said blood sample, said hemolytic agent stored in said predetermined reagent container and a quantity of said diluting solution smaller than said predetermined quantity of diluting solution for the first measurement sample, such that said dilution magnification of said hemolytic agent in said second measurement sample is smaller than said dilution magnification of said hemolytic agent in said first measurement sample, and wherein the staining agent includes a DNA-selective fluorescent dye.