Provided are: an endothelin receptor antagonist composition； a use of said composition as a substance for inhibiting the binding of endothelin to endothelin receptors； and a method for inhibiting the binding of endothelin receptor-binding substances to endothelin receptors. It has been discovered that a specific cyclic dipeptide or a salt thereof exhibits endothelin receptor antagonistic action. The present invention provides a novel and effective means for contributing to the suppression of blood pressure elevation, the improvement of blood flow, the suppression of cerebral oedema formation, and the suppression of epidermal pigmentation.
