An antibody or an antigen binding fragment thereof, which can specifically bind to HBsAg, comprising: (a) three complementarity determining regions (CDRs) of heavy chain variable region selected from the group consisting of: (i) VH CDR1, consisting of the following sequence: SEQ ID NO: 3, or a sequence that differs from SEQ ID NO:3 by 1 or 2 substitutions selected from the group consisting of: R or Y at H31; and W at H32; (ii) VH CDR2, consisting of the following sequence: SEQ ID NO: 4, or a sequence that differs from SEQ ID NO:4 by 1, 2, 3 or 4 substitutions selected from the group consisting of: T at H56; V or N at H57; L at H58; K at H64; and S at H65; (iii) VH CDR3, consisting of the following sequence: SEQ ID NO: 5; and (b) three CDRs of light chain variable region selected from the group consisting of: (iv) VL CDR1, consisting of the following sequence: SEQ ID NO: 6, or a sequence that differs from SEQ ID NO:6 by 1 or 2 substitutions selected from the group consisting of: P or T at L27; and S or N at L30; (v) VL CDR2, consisting of the following sequence: SEQ ID NO: 7, and (vi) VL CDR3, consisting of the following sequence: SEQ ID NO: 8; and wherein the antibody or an antigen binding fragment thereof comprises: VH as set forth in SEQ ID NO: 72 and VL as set forth in SEQ ID NO: 201; VH as set forth in SEQ ID NO: 69 and VL as set forth in SEQ ID NO: 189; VH as set forth in SEQ ID NO: 73 and VL as set forth in SEQ ID NO: 202; VH as set forth in SEQ ID NO: 91 and VL as set forth in SEQ ID NO: 205; VH as set forth in SEQ ID NO: 73 and VL as set forth in SEQ ID NO: 205; VH as set forth in SEQ ID NO: 36 and VL as set forth in SEQ ID NO: 187; VH as set forth in SEQ ID NO: 36 and VL as set forth in SEQ ID NO: 189; VH as set forth in SEQ ID NO: 20 and VL as set forth in SEQ ID NO: 187; or, VH as set forth in SEQ ID NO: 41 and VL as set forth in SEQ ID NO: 187. (a) three complementarity determining regions (CDRs) of heavy chain variable region selected from the group consisting of: (i) VH CDR1, consisting of the following sequence: SEQ ID NO: 3, or a sequence that differs from SEQ ID NO:3 by 1 or 2 substitutions selected from the group consisting of: R or Y at H31; and W at H32; (ii) VH CDR2, consisting of the following sequence: SEQ ID NO: 4, or a sequence that differs from SEQ ID NO:4 by 1, 2, 3 or 4 substitutions selected from the group consisting of: T at H56; V or N at H57; L at H58; K at H64; and S at H65; (iii) VH CDR3, consisting of the following sequence: SEQ ID NO: 5; and (i) VH CDR1, consisting of the following sequence: SEQ ID NO: 3, or a sequence that differs from SEQ ID NO:3 by 1 or 2 substitutions selected from the group consisting of: R or Y at H31; and W at H32; R or Y at H31; and W at H32; (ii) VH CDR2, consisting of the following sequence: SEQ ID NO: 4, or a sequence that differs from SEQ ID NO:4 by 1, 2, 3 or 4 substitutions selected from the group consisting of: T at H56; V or N at H57; L at H58; K at H64; and S at H65; T at H56; V or N at H57; L at H58; K at H64; and S at H65; (iii) VH CDR3, consisting of the following sequence: SEQ ID NO: 5; (b) three CDRs of light chain variable region selected from the group consisting of: (iv) VL CDR1, consisting of the following sequence: SEQ ID NO: 6, or a sequence that differs from SEQ ID NO:6 by 1 or 2 substitutions selected from the group consisting of: P or T at L27; and S or N at L30; (v) VL CDR2, consisting of the following sequence: SEQ ID NO: 7, and (vi) VL CDR3, consisting of the following sequence: SEQ ID NO: 8; and (iv) VL CDR1, consisting of the following sequence: SEQ ID NO: 6, or a sequence that differs from SEQ ID NO:6 by 1 or 2 substitutions selected from the group consisting of: P or T at L27; and S or N at L30; P or T at L27; and S or N at L30; (v) VL CDR2, consisting of the following sequence: SEQ ID NO: 7, and (vi) VL CDR3, consisting of the following sequence: SEQ ID NO: 8; and VH as set forth in SEQ ID NO: 72 and VL as set forth in SEQ ID NO: 201; VH as set forth in SEQ ID NO: 69 and VL as set forth in SEQ ID NO: 189; VH as set forth in SEQ ID NO: 73 and VL as set forth in SEQ ID NO: 202; VH as set forth in SEQ ID NO: 91 and VL as set forth in SEQ ID NO: 205; VH as set forth in SEQ ID NO: 73 and VL as set forth in SEQ ID NO: 205; VH as set forth in SEQ ID NO: 36 and VL as set forth in SEQ ID NO: 187; VH as set forth in SEQ ID NO: 36 and VL as set forth in SEQ ID NO: 189; VH as set forth in SEQ ID NO: 20 and VL as set forth in SEQ ID NO: 187; or, VH as set forth in SEQ ID NO: 41 and VL as set forth in SEQ ID NO: 187.