The present invention addresses the problem of providing: a novel peptide which can exert the medicinal effect or efficacy thereof rapidly and has a long duration of remission； and a medicine and an external preparation, particularly a prophylactic or therapeutic agent for dermatitis, rough skin, rhinitis, alopecia or thinning hair, a hair growth agent, an anti-depilation agent, an antipruritic agent, a skin care product and the like, each of which contains the peptide. According to the present invention, the problem can be solved by providing a cyclic peptide comprising the amino acid sequence represented by formula I wherein the amino acid sequence does not contain a peptide bond other than peptide bonds formed between amino acid residues that constitute the amino acid sequence, or a derivative of the cyclic peptide, or a pharmaceutically acceptable salt of the cyclic peptide or the derivative.
