A method for distinguishing erythrocytes in a biological specimen, includes preparing a sample liquid so as to cause damage to a cell membrane of yeast-like fungi without hemolyzing erythrocytes in a biological specimen and to stain the yeast-like fungi with a fluorescent dye; detecting a first information and a second information from a particle in the sample liquid, wherein the first information reflects a size of the particle and the second information reflects a degree of fluorescent staining of the particle; and distinguishing the erythrocytes from the yeast-like fungi based on the first information and second information detected. An apparatus, a reagent kit and a reagent for carrying out the method are also disclosed.