It is provided a pharmaceutical composition stably containing ghrelin or its derivative, which is an endogenous growth hormone secretagogue (GHS) to a growth hormone secretagogue-receptor (GHS-R), comprising a aqueous solution containing the ghrelins having pH range of 2 to 7, wherein the aqueous solution having pH range of 2 to 7 is a buffer solution, especially, glycine hydrochloride buffer, acetate buffer, citrate buffer, lactate buffer, phosphate buffer, citric acid-phosphate buffer, phosphate-acetate-borate buffer or phthalate buffer, and the concentration of the ghrelins in the solution is from 0.03 nmol/mL to 6 .mu.mol/mL.