The present invention relates to novel anti-CD40 antibodies and a use thereof and, more specifically, provided are a pharmaceutical composition for treating or preventing autoimmune diseases and a composition for inhibiting immune rejection during organ transplantation, both compositions containing, as an active ingredient, novel anti-CD40 antibodies that specifically bind to a novel epitope of CD40. Novel anti-CD40 antibodies of the present invention directly target CD40, but not CD40 ligands, and block the signaling of CD40-CD154 without stimulating platelets so as to exhibit excellent antagonistic effects, thereby being expected to be usable as a preparation effective in the treatment of autoimmune diseases and the inhibition of organ transplantation rejection.