The present invention addresses the problem of providing: a novel peptide having a high medicinal effect and high efficacy； and a medicine and an external preparation, particularly a prophylactic or therapeutic agent for dermatitis, rhinitis and alopecia, a hair regrowth agent, a hair growth agent, an antipruritic agent, a skin care product and the like, each comprising the peptide. The present invention achieves the problem by providing a cyclic peptide, a derivative of the cyclic peptide or a pharmaceutically acceptable salt of the cyclic peptide or the derivative, wherein the cyclic peptide comprises the amino acid sequence represented by formula I and the amino acid sequence does not have a peptide bond between amino acid residues other than amino acid residues constituting the amino acid sequence.
