The invention provides monoclonal antibodies, which specifically react with a Fas ligand, or active fragments thereof, a production process of the monoclonal antibodies, which specifically react with a Fas ligand, hybridomas separately producing a monoclonal antibody, which specifically reacts with a Fas ligand present on a cell surface, a method of detecting a Fas ligand in a solution, and a kit for use in detecting a Fas ligand, comprising plurality of monoclonal antibodies against Fas ligand in combination.