A blood analyzer includes a sample preparation portion preparing a first measurement sample containing a blood sample and a hemolytic agent and a second measurement sample containing the blood sample, the same hemolytic agent as the hemolytic agent and a staining agent and a control portion classifying white blood cells in the first measurement sample into at least four groups of monocytes, neutrophils, eosinophils and a group of the others on the basis of fluorescent information and two types of scattered light information generated by a light information generation portion and classifying blood cells in the second measurement sample into malaria-infected red blood cells and non-malaria-infected red blood cells on the basis of fluorescent information and scattered light information generated by the light information generation portion.