Discovered is a pharmaceutical composition that sustainedly releases a drug over a long time period after being administered into a body. Provided is the pharmaceutical composition comprising the drug and a polypeptide represented by Ac-(Arg-Ala-Asp-A1a)4-NH2, the pharmaceutical composition further comprising an organic solvent selected from the group consisting of polyethylene glycol, dimethyl sulfoxide, glycofurol, and N-methyl pyrrolidone.
