[Problem] To provide a method that efficiently produces antigen-specific monoclonal antibodies from a wide range of animal species, and to provide a new antigen-specific monoclonal antibody using this technique. [Solution] A nonhuman animal is immunized with a target antigen, lymph fluid or the like is collected from the immunized nonhuman animal, or lymph fluid or the like is collected from a human having antibodies to the target antigen, the collected lymph fluid or the like is combined with (1) a labeled target antigen and (2) a marker that can selectively binds to plasma cells and/or plasmablasts, and cells that have bound to (1) the labeled target antigen and (2) the marker are then selected. The plasma cells and or the plasmablasts that have specifically bound to the target antigen by the method are selected, an gene of an antibody for the target antigen is collected from the selected cells, the base sequence thereof is identified, an antibody or antibody fragment is prepared on the basis of the base sequence of the identified gene, and an antibody or antibody fragment specific to the target antigen is produced.