The present invention relates to an antibody against epidermal growth factor receptor variant III (EGFRvIII) or an antigen-binding fragment thereof, a nucleic acid encoding the same, a vector carrying the nucleic acid, a cell transformed with the vector, a method for preparing the antibody or an antigen-binding fragment thereof, a composition thereof for preventing or treating cancer, a composition for diagnosing cancer, and a kit for diagnosing cancer.
