An antibody or an antigen-binding fragment thereof that specifically binds to ErbB3, comprising heavy chain complementarity determining regions (CDR-Hs) and light chain complementarity determining regions (CDR-Ls), wherein the antibody or antigen-binding fragment thereof is selected from the group consisting of: an antibody or antigen-binding fragment thereof comprising a CDR-H1 having the sequence of SEQ ID NO: 61, a CDR-H2 having the sequence of SEQ ID NO: 70, a CDR-H3 having the sequence of SEQ ID NO: 78, a CDR-L1 having the sequence of SEQ ID NO: 86, a CDR-L2 having the sequence of SEQ ID NO: 88, and a CDR-L3 having the sequence of SEQ ID NO: 95; an antibody or antigen-binding fragment thereof comprising a CDR-H1 having the sequence of SEQ ID NO: 61, a CDR-H2 having the sequence of SEQ ID NO: 73, a CDR-H3 having the sequence of SEQ ID NO: 78, a CDR-L1 having the sequence of SEQ ID NO: 86, a CDR-L2 having the sequence of SEQ ID NO: 88, and a CDR-L3 having the sequence of SEQ ID NO: 94; an antibody or antigen-binding fragment thereof comprising a CDR-H1 having the sequence of SEQ ID NO: 61, a CDR-H2 having the sequence of SEQ ID NO: 74, a CDR-H3 having the sequence of SEQ ID NO: 79, a CDR-L1 having the sequence of SEQ ID NO: 87, a CDR-L2 having the sequence of SEQ ID NO: 89, and a CDR-L3 having the sequence of SEQ ID NO: 94; an antibody or antigen-binding fragment thereof comprising a CDR-H1 having the sequence of SEQ ID NO: 63, a CDR-H2 having the sequence of SEQ ID NO: 76, a CDR-H3 having the sequence of SEQ ID NO: 81, a CDR-L1 having the sequence of SEQ ID NO: 86, a CDR-L2 having the sequence of SEQ ID NO: 92, and a CDR-L3 having the sequence of SEQ ID NO: 100; an antibody or antigen-binding fragment thereof comprising a CDR-H1 having the sequence of SEQ ID NO: 66, a CDR-H2 having the sequence of SEQ ID NO: 76, a CDR-H3 having the sequence of SEQ ID NO: 81, a CDR-L1 having the sequence of SEQ ID NO: 86, a CDR-L2 having the sequence of SEQ ID NO: 92, and a CDR-L3 having the sequence of SEQ ID NO: 100; an antibody or antigen-binding fragment thereof comprising a CDR-H1 having the sequence of SEQ ID NO: 61, a CDR-H2 having the sequence of SEQ ID NO: 70, a CDR-H3 having the sequence of SEQ ID NO: 78, a CDR-L1 having the sequence of SEQ ID NO: 86, a CDR-L2 having the sequence of SEQ ID NO: 88, and a CDR-L3 having the sequence of SEQ ID NO: 95; an antibody or antigen-binding fragment thereof comprising a CDR-H1 having the sequence of SEQ ID NO: 61, a CDR-H2 having the sequence of SEQ ID NO: 73, a CDR-H3 having the sequence of SEQ ID NO: 78, a CDR-L1 having the sequence of SEQ ID NO: 86, a CDR-L2 having the sequence of SEQ ID NO: 88, and a CDR-L3 having the sequence of SEQ ID NO: 94; an antibody or antigen-binding fragment thereof comprising a CDR-H1 having the sequence of SEQ ID NO: 61, a CDR-H2 having the sequence of SEQ ID NO: 74, a CDR-H3 having the sequence of SEQ ID NO: 79, a CDR-L1 having the sequence of SEQ ID NO: 87, a CDR-L2 having the sequence of SEQ ID NO: 89, and a CDR-L3 having the sequence of SEQ ID NO: 94; an antibody or antigen-binding fragment thereof comprising a CDR-H1 having the sequence of SEQ ID NO: 63, a CDR-H2 having the sequence of SEQ ID NO: 76, a CDR-H3 having the sequence of SEQ ID NO: 81, a CDR-L1 having the sequence of SEQ ID NO: 86, a CDR-L2 having the sequence of SEQ ID NO: 92, and a CDR-L3 having the sequence of SEQ ID NO: 100; an antibody or antigen-binding fragment thereof comprising a CDR-H1 having the sequence of SEQ ID NO: 66, a CDR-H2 having the sequence of SEQ ID NO: 76, a CDR-H3 having the sequence of SEQ ID NO: 81, a CDR-L1 having the sequence of SEQ ID NO: 86, a CDR-L2 having the sequence of SEQ ID NO: 92, and a CDR-L3 having the sequence of SEQ ID NO: 100; <EOS>