The present disclosure relates to a peptide for inhibiting a TLR4 signaling pathway, a TLR4 antagonist including the peptide, and a composition for preventing or treating autoimmune diseases and inflammatory diseases. More specifically, the present disclosure relates to a peptide which binds to a TLR4/MD2 composite to inhibit the secretion of interleukin-6 (IL-6), NO, and ROS, and the activation of NFºB and MAPKs, a TLR4 antagonist including the peptide, and a composition for preventing or treating autoimmune diseases and inflammatory diseases. The peptide according to the present disclosure has an excellent effect of inhibiting the secretion of interleukin-6 (IL-6), NO, and ROS, and the activation of NFºB and MAPKs by inhibiting a TLR4 signaling pathway induced by a liphopolysaccharide (LPS), and thus can be favorably used as a composition for preventing or treating autoimmune diseases and inflammatory diseases occurring by the TLR4 signaling pathway.
