PURPOSE: To obtain the titled antibody to bovine serum albumin, by cultivating a hybridoma capable of producing a monoclonal antibody to bovine serum albumin in a medium, etc., forming and accumulating the antibody, collecting it form the culture solution.

CONSTITUTION: A splenocyte obtained by immunizing a mouse with bovine serum albumin and a bone tumor cell of mouse are fused to give a hybridoma capable of producing a monoclonal antibody to bovine serum albumin. The hybridoam is cultivated in a medium or it is transplanted into an abdominal cavity of mouse and ascites tumor is developed, so that the monoclonal antibody is formed and accumulated in the culture solution or in the ascites, and the monoclonal antibody to bovine serum albumin is collected from the culture solution or the ascites. The antibody is subjected to affinity chromatography, so that the bovine serum albumin can be separated from a substance containing it and purified.