Abstract: A monoclonal antibody against human manganese-superoxide dismutase characterized in that it is produced by a cell line which has been obtained by immunization of a mouse with human Mn-SOD and then fusion of lymphocytes obtained from the mouse with mouse myeloma cells, and has high specificity against human Mn-SOD; a method for producing a monoclonal antibody against human Mn-SOD having high specificity against human Mn-SOD, which comprises culturing the cell line obtained by immunization of a mouse with human Mn-SOD and then cell fusion of lymphocytes obtained from the mouse with mouse myeloma cells; a kit for assaying human Mn-SOD, comprising:(a) a monoclonal antibody having very high specific immuno-reactivity against human Mn-SOD; and(b) a reagent of a monoclonal antibody having very high specific immuno-reactivity against human Mn-SOD labelled with an enzyme (enzyme labelled antibody); a method for assaying human Mn-SOD use of the kit; a novel diagnostic method of human epithelial ovarian cancer, which co