Disclosed are an anti-PD-L1 antibody or an antigen-binding fragment thereof, a nucleic acid encoding the same, a vector including the nucleic acid, a cell transformed with the vector, a method for producing the antibody or an antigen-binding fragment thereof, a pharmaceutical composition for preventing or treating cancer containing the same, and a composition for co-administration with an antibody other than an antibody binding to PD-L1, containing the same.