A blood cell analyzer comprising: a first detection unit for electrically detecting blood cells in blood sample; a second detection unit for optically detecting blood cells in blood sample; a volume information obtainer for obtaining volume information of red blood cells based on the electrically detected blood cells by the first detection unit; a scattered light intensity information obtainer for obtaining a scattered light intensity of red blood cells based on the optically detected blood cells by the second detection unit; a display unit; and a data processor configured to prepare a first histogram of the volume information of each of the red blood cells obtained by the volume information obtainer, a second histogram of the scattered light intensity information of each of the red blood cells obtained by the scattered light intensity information obtainer and a screen for displaying on the display unit, the screen including the first and second histograms, characterized in that: the first histogram contains first and second demarcation lines corresponding to first and second threshold values, and the second histogram contains third and fourth demarcation lines corresponding to third and fourth threshold values, wherein the data processor is configured to calculate a percentage of red blood cells which have volume information that is less than the first threshold value relative to all red blood cells (MicroR), a percentage of red blood cells which have volume information that is greater than the second threshold value relative to all red blood cells (MacroR), a percentage of red blood cells which have scattered light intensity information that is less than the third threshold value relative to all red blood cells (LScRBC), and a percentage of red blood cells which have scattered light intensity information that is greater than the fourth threshold value relative to all red blood cells (HScRBC), and wherein the data processor prepares the screen including the first and second histograms, the calculated MicroR, the calculated MacroR, the calculated LScRBC and the calculated HScRBC. a first detection unit for electrically detecting blood cells in blood sample; a second detection unit for optically detecting blood cells in blood sample; a volume information obtainer for obtaining volume information of red blood cells based on the electrically detected blood cells by the first detection unit; a scattered light intensity information obtainer for obtaining a scattered light intensity of red blood cells based on the optically detected blood cells by the second detection unit; a display unit; and a data processor configured to prepare a first histogram of the volume information of each of the red blood cells obtained by the volume information obtainer, a second histogram of the scattered light intensity information of each of the red blood cells obtained by the scattered light intensity information obtainer and a screen for displaying on the display unit, the screen including the first and second histograms, characterized in that: the first histogram contains first and second demarcation lines corresponding to first and second threshold values, and the second histogram contains third and fourth demarcation lines corresponding to third and fourth threshold values, wherein the data processor is configured to calculate a percentage of red blood cells which have volume information that is less than the first threshold value relative to all red blood cells (MicroR), a percentage of red blood cells which have volume information that is greater than the second threshold value relative to all red blood cells (MacroR), a percentage of red blood cells which have scattered light intensity information that is less than the third threshold value relative to all red blood cells (LScRBC), and a percentage of red blood cells which have scattered light intensity information that is greater than the fourth threshold value relative to all red blood cells (HScRBC), and wherein the data processor prepares the screen including the first and second histograms, the calculated MicroR, the calculated MacroR, the calculated LScRBC and the calculated HScRBC. the first histogram contains first and second demarcation lines corresponding to first and second threshold values, and the second histogram contains third and fourth demarcation lines corresponding to third and fourth threshold values, wherein the data processor is configured to calculate a percentage of red blood cells which have volume information that is less than the first threshold value relative to all red blood cells (MicroR), a percentage of red blood cells which have volume information that is greater than the second threshold value relative to all red blood cells (MacroR), a percentage of red blood cells which have scattered light intensity information that is less than the third threshold value relative to all red blood cells (LScRBC), and a percentage of red blood cells which have scattered light intensity information that is greater than the fourth threshold value relative to all red blood cells (HScRBC), and wherein the data processor prepares the screen including the first and second histograms, the calculated MicroR, the calculated MacroR, the calculated LScRBC and the calculated HScRBC.