Provided are an anti-CD40L antibody and an antigen-binding fragment thereof for treating a disease or disorder associated with CD40L, a composition comprising such an antibody or an antigen-binding fragment, an anti-CD40L antibody having a low effector function, and a method of using the same. [Selection diagram] Figure 1ACD40L関連の疾患または障害を治療するための抗CD40L抗体及びその抗原結合断片、かかる抗体または抗原結合断片を含む組成物、低エフェクター機能の抗CD40L抗体、ならびにその使用方法を提供する。【選択図】図1A