It is an object of the present invention to provide an immunodeficient animal capable of generating human-derived lymphoid cells, a human-derived lymphoid cell, and a method for producing a human antigen-specific antibody. The means for solving the aforementioned object is: an immature immunodeficient mammal into which human-derived hematopoietic precursor cells have been transplanted, and which is able to generate said human-derived hematopoietic cells or immunocompetent cells; and a method for producing a human-derived antibody, which is characterized in that it comprises recovering immunocompetent cells from the above-described mammal, culturing the immunocompetent cells, and collecting a human-derived antibody from the obtained culture product.