An antibody that binds human PD-1 (SEQ ID NO: 1), comprising a light chain and a heavy chain, wherein the light chain comprises light chain complementarity determining regions LCDR1, LCDR2, and LCDR3 and the heavy chain comprises heavy chain complementarity determining regions HCDR1, HCDR2, and HCDR3, wherein: (i) LCDR1, LCDR2, and LCDR3 consist of the amino acid sequences RASQSVSSYLA (SEQ ID NO: 14), YDASKRAT (SEQ ID NO: 15), and DQRNNWPLT (SEQ ID NO: 16), respectively, and HCDR1, HCDR2, and HCDR3 consist of the amino acid sequences KASGYTFTSYYMH (SEQ ID NO: 2), IINPSGGSTSYAQKFQG (SEQ ID NO: 8), and AKEGVADGYGLVDV (SEQ ID NO: 13), respectively; (ii) LCDR1, LCDR2, and LCDR3 consist of the amino acid sequences RASQSVSSYLA (SEQ ID NO: 14), YDASKRAT (SEQ ID NO: 15), and DQRNNWPLT (SEQ ID NO: 16), respectively, and HCDR1, HCDR2, and HCDR3 consist of the amino acid sequences KASGYTFEGYYMH (SEQ ID NO: 3), IINPEGGETSYAQKFQG (SEQ ID NO: 9), and AKEGVADGYGLVDV (SEQ ID NO: 13), respectively; (iii) LCDR1, LCDR2, and LCDR3 consist of the amino acid sequences RASQSVSSYLA (SEQ ID NO: 14), YDASKRAT (SEQ ID NO: 15), and DQRNNWPLT (SEQ ID NO: 16), respectively, and HCDR1, HCDR2, and HCDR3 consist of the amino acid sequences KASGYTFTAQYMH (SEQ ID NO: 4), IINPSGGETGYAQKFQG (SEQ ID NO: 10), and AKEGVADGYGLVDV (SEQ ID NO: 13), respectively; (iv) LCDR1, LCDR2, and LCDR3 consist of the amino acid sequences RASQSVSSYLA (SEQ ID NO: 14), YDASKRAT (SEQ ID NO: 15), and DQRNNWPLT (SEQ ID NO: 16), respectively, and HCDR1, HCDR2, and HCDR3 consist of the amino acid sequences KASGYTFEKYYMH (SEQ ID NO: 5), IINPDGGSTGYAQKFQG (SEQ ID NO: 12), and AKEGVADGYGLVDV (SEQ ID NO: 13), respectively; (v) LCDR1, LCDR2, and LCDR3 consist of the amino acid sequences RASQSVSSYLA (SEQ ID NO: 14), YDASKRAT (SEQ ID NO: 15), and DQRNNWPLT (SEQ ID NO: 16), respectively, and HCDR1, HCDR2, and HCDR3 consist of the amino acid sequences KASGYTFTSNYMH (SEQ ID NO: 6), IINPSEGSTGYAQKFQG (SEQ ID NO: 11), and AKEGVADGYGLVDV (SEQ ID NO: 13), respectively; or (vi) LCDR1, LCDR2, and LCDR3 consist of the amino acid sequences RASQSVSSYLA (SEQ ID NO: 14), YDASKRAT (SEQ ID NO: 15), and DQRNNWPLT (SEQ ID NO: 16), respectively, and HCDR1, HCDR2, and HCDR3 consist of the amino acid sequences KASGYTFSAYYMH (SEQ ID NO: 7), IINPDGGSTGYAQKFQG (SEQ ID NO: 12), and AKEGVADGYGLVDV (SEQ ID NO: 13), respectively. (i) LCDR1, LCDR2, and LCDR3 consist of the amino acid sequences RASQSVSSYLA (SEQ ID NO: 14), YDASKRAT (SEQ ID NO: 15), and DQRNNWPLT (SEQ ID NO: 16), respectively, and HCDR1, HCDR2, and HCDR3 consist of the amino acid sequences KASGYTFTSYYMH (SEQ ID NO: 2), IINPSGGSTSYAQKFQG (SEQ ID NO: 8), and AKEGVADGYGLVDV (SEQ ID NO: 13), respectively; (ii) LCDR1, LCDR2, and LCDR3 consist of the amino acid sequences RASQSVSSYLA (SEQ ID NO: 14), YDASKRAT (SEQ ID NO: 15), and DQRNNWPLT (SEQ ID NO: 16), respectively, and HCDR1, HCDR2, and HCDR3 consist of the amino acid sequences KASGYTFEGYYMH (SEQ ID NO: 3), IINPEGGETSYAQKFQG (SEQ ID NO: 9), and AKEGVADGYGLVDV (SEQ ID NO: 13), respectively; (iii) LCDR1, LCDR2, and LCDR3 consist of the amino acid sequences RASQSVSSYLA (SEQ ID NO: 14), YDASKRAT (SEQ ID NO: 15), and DQRNNWPLT (SEQ ID NO: 16), respectively, and HCDR1, HCDR2, and HCDR3 consist of the amino acid sequences KASGYTFTAQYMH (SEQ ID NO: 4), IINPSGGETGYAQKFQG (SEQ ID NO: 10), and AKEGVADGYGLVDV (SEQ ID NO: 13), respectively; (iv) LCDR1, LCDR2, and LCDR3 consist of the amino acid sequences RASQSVSSYLA (SEQ ID NO: 14), YDASKRAT (SEQ ID NO: 15), and DQRNNWPLT (SEQ ID NO: 16), respectively, and HCDR1, HCDR2, and HCDR3 consist of the amino acid sequences KASGYTFEKYYMH (SEQ ID NO: 5), IINPDGGSTGYAQKFQG (SEQ ID NO: 12), and AKEGVADGYGLVDV (SEQ ID NO: 13), respectively; (v) LCDR1, LCDR2, and LCDR3 consist of the amino acid sequences RASQSVSSYLA (SEQ ID NO: 14), YDASKRAT (SEQ ID NO: 15), and DQRNNWPLT (SEQ ID NO: 16), respectively, and HCDR1, HCDR2, and HCDR3 consist of the amino acid sequences KASGYTFTSNYMH (SEQ ID NO: 6), IINPSEGSTGYAQKFQG (SEQ ID NO: 11), and AKEGVADGYGLVDV (SEQ ID NO: 13), respectively; or (vi) LCDR1, LCDR2, and LCDR3 consist of the amino acid sequences RASQSVSSYLA (SEQ ID NO: 14), YDASKRAT (SEQ ID NO: 15), and DQRNNWPLT (SEQ ID NO: 16), respectively, and HCDR1, HCDR2, and HCDR3 consist of the amino acid sequences KASGYTFSAYYMH (SEQ ID NO: 7), IINPDGGSTGYAQKFQG (SEQ ID NO: 12), and AKEGVADGYGLVDV (SEQ ID NO: 13), respectively.