The present invention relates to a sustained-release formulation comprising a metastin derivative and a lactic acid-glycolic acid copolymer having a weight average molecular weight of about 5,000 to about 40,000 or a salt thereof. The sustained-release formulation of the present invention slowly and stably release compound (I) or a salt thereof for a long time and exerts a medicinal effect of compound (I) or a salt thereof for a long time. Furthermore, the sustained-release formulation of the present invention, which improves patients convenience by reducing the number of administration times, is an excellent formulation as a clinical medicine.Una formulación de liberación sostenida que comprende un compuesto representado por la Fórmula: Ac-D-Tyr-Hyp-Asn-Thr-Phe-AzaGly-Leu-Arg(Me)-Trp-NH2 (I) o una sal del mismo y un copolímero de ácido láctico-ácido glicólico que tiene un peso molecular medio ponderado de 5.000 a 40.000, o una sal del mismo.
