The present invention relates to novel polypeptide for binding to a complement protein C5a. More particularly, the present invention relates to polypeptide which can be bound to a complement protein C5a and inhibit the activation of same, polynucleotide which codes for the polypeptide, a recombinant vector which comprises the polynucleotide, a recombinant microorganism to which the recombinant vector has been introduced, a method for producing the polypeptide by means of the recombinant microorganism, and a pharmaceutical composition, for treating immune diseases or sepsis, containing the polypeptide. A polypeptide, according to the present invention, can be bound to a complement protein C5a, with higher affinity compared to being bound to a complement protein C5a receptor which is present in nature, and inhibits the activation of same, thus being widely utilized for development of formulation for preventing or treating diseases related to a complement protein C5a.