The present invention relates to an anti-MUC1 antibody binding specifically to Mucin 1 (MUC1) or an antigen-binding fragment thereof, an antibody-drug conjugate comprising the antibody or the antigen-binding fragment thereof, and a pharmaceutical composition for prevention or treatment of cancer comprising the conjugate. According to the present invention, the antibody shows outstanding affinity and binding force to MUC1 and the antibody-drug conjugate in which the antibody or the antigen-binding fragment thereof is conjugated with a drug can bind specifically to a MUC1-expressing cell to specifically or selectively transfer the drug with efficacy. Therefore, the anti-MUC1 antibody and the antibody-drug conjugate according to the present invention can be usefully applied to the treatment of a MUC1-related disease, for example, cancer.