[PROBLEM] To provide a monoclonal antibody against a biomarker which shows high specificity and can be effectively used in detection and diagnosis of various lesions relevant to various kinds of carcinomas and foci of necrosis, and so forth.[MEANS] A monoclonal antibody against a necrosis marker consisting the following amino acid sequence: (1) the amino acid sequence of SEQ ID NO: 1, or (2) an amino acid sequence having substitution, deletion and/or insertion of one or several amino acid residues in the amino acid sequence of (1) or sharing a homology of 90% or more with the amino acid sequence of (1), and showing the same function, activity or property as that of the amino acid sequence of (1) as a protein.