TNFα (Tumor Necrosis Factor alpha) is a multifunctional cytokine that plays an important role in inflammation, regulation of immune function, and induction of apoptosis. While an optimal level of TNFα signaling is beneficial, the over production of TNFα is involved in the pathogenesis of autoimmune diseases associated with inflammation, including rheumatoid arthritis, Crohn’s disease, and psoriasis. Severe symptoms are already treated with TNFα-antagonists that inhibit the interaction between TNFα and its receptors (TNFRs), for instance, anti-TNFα monoclonal antibodies (Infliximab, Adalimumab) or recombinant receptor (Etanercept). However, the use of these large molecules has several disadvantages, such as poor stability, high production cost by mammalian cells. To overcome these limitations, it is necessary to develop low molecular weight inhibitors that are stable and low-cost. In this study, we performed in vitro selection and functional analysis of TNFα-binding cyclic peptide.