PURPOSE: The titled monoclonal antibody, obtained from hybridoma cells prepared by fusing cells, obtained by immunizing an animal with bilirubin, and capable of producing antibodies to tumorous cells having the ability to divide and multiply in the cultivation system, and against bilirubin.

CONSTITUTION: An animal is immunized with bilirubin to give cells capable of producing antibodies, e.g. mouse splenic cells, which are then fued to tumorous cells having the ability to divide and multiply in the cultivation system, e.g. myelomatous cells, to give hybridoma cells. The aimed monoclonal antibodies against the bilirubin are obtained from the resultant hybridoma cells. The abovementioned antibodies are capable of acting respective specific bilirubin with high specificity, and direct quantitative analysis of the respective bilirubin can be efficiently carried out in a short time. Thus, the cause and conditions of jaundice can be accurately analyzed. Furthermore, discrimination and diagnosis of hemopathy, hepatopathy or malignant tumors, etc. are possible.