A cyclic peptide or a salt thereof, the cyclic peptide having an amino acid sequence represented by the following formula (1): X-Leu-Val-Y1-Y2 (1) (where X is Lys, Arg, His, Ala , Gly, Ser or Thr； and Y1 and Y2, which are identical or different from each other, each represent a group represented by the following formula (2): (where, in formula (2), Ar1 represents a hydrocarbon group aromatic or an aromatic heterocyclic group (the aromatic hydrocarbon group or the aromatic heterocyclic group may have 1 to 5 substituents selected from the group consisting of an alkyl group, a cycloalkyl group, a haloalkyl group, a halogen atom, a hydroxy group , an alkoxy group, an aromatic hydrocarbon group, an aromatic heterocyclic group and an amino group)； R 1 represents a hydrogen atom, an alkyl group, a cycloalkyl group, a haloalkyl group, an aromatic hydrocarbon group or an aromatic heterocyclic group ico (the aromatic hydrocarbon group or the aromatic heterocyclic group may have 1 to 5 substituents selected from the group consisting of an alkyl group, a cycloalkyl group, a haloalkyl group, a halogen atom, a hydroxy group, an alkoxy group, a aromatic hydrocarbon group, an aromatic heterocyclic group and an amino group)； and n is an integer from 0 to 2)), wherein the α-amino group at the amino end of the amino acid sequence is linked, via a peptide bond, to the carboxyl group at the carboxyl end of the amino acid sequence .Un péptido cíclico o una sal del mismo, teniendo el péptido cíclico una secuencia de aminoácidos representada por la siguiente fórmula (1): X-Leu-Val-Y1-Y2 (1) (en donde X es Lys, Arg, His, Ala, Gly, Ser o Thr； e Y1 e Y2, que son idénticos o diferentes entre sí, representan cada uno un grupo representado por la siguiente fórmula (2): (en donde, en la fórmula (2), Ar1 representa un grupo hidrocarbonado aromático o un grupo heterocíclico aromático (el grupo hidrocarbonado aromático o el grupo heterocíclico aromático pueden tener de 1 a 5 sustituyentes selecciona
