Disclosed is a blood analyzer including a specimen preparation unit that prepares a measurement specimen by mixing a hemolytic agent that hemolyzes red blood cells, a staining dye that dyes nucleic acids, and a blood specimen; a detector that detects intensity of side scattered light and intensity of fluorescence generated with application of light from the measurement specimen prepared by the specimen preparation unit; and an analysis unit that discriminates white blood cells from giant platelets based on the intensity of side scattered light and the intensity of fluorescence detected by the detector, and counts the white blood cells.