An antibody-like protein is formed by self-assembly of a plurality of ferritin monomers including at least CDR-ferritin monomers having a complementarity-determining region of an antibody fused thereto whereby the antibody-like protein has the complementarity-determining regions present at a high density on the surface or outside thereof so that even some of the complementarity-determining regions, such as HCDR3, etc., can bind to an antigen at an affinity level similar to that of the antibody, and the antibody-like protein possesses a structural feature advantageous for binding simultaneously to a plurality of antigens, and as such, has remarkably improved binding avidity, compared to the antibody. The antibody-like protein of the present invention is an antibody substitute that can be utilized in antibody-based uses and fields.