PURPOSE: To distinguish blood between a human being and animals other than human beings by using a red blood corpuscle agglutinin which is produced by microorganism belonging to conidiobolus group.

CONSTITUTION: The microorganism used for producing a red blood corpuscle agglutinin can be whatever only belongs to conidiobolus group and has such an ability. For example, the microorganism is inoculated and cultured in a medium which contains those demanded by bacteria used such as glucose, sugar and milk sugar using conidiobolus lamprauges CBS151 and 56 as carbon source, ammonium salt, urea, peptone, yeast extraction and melt extraction as nitrogen source and other inorganic salts to be added. Then, CLA is separated and refined from the culture.