PROBLEM TO BE SOLVED : To provide a prophylactic or therapeutic agent exhibiting good oral absorption in mood disorder (including depression and bipolar disorder), anxiety disorder, cognitive disorder, developmental disorder, Alzheimer' s disease, Parkinson' s disease, sleep disorder, Huntington chorea, eating disorder, drug dependence, epilepsy, cerebral infarction, cerebral ischemia, cerebral edema, head injury, inflammation, immunity related disease, and the like.SOLUTION : A pharmaceutical contains, as an active ingredient, an amino acid derivative prodrug represented by general formula (I-A) being a prodrug of an amino acid derivative being a group 2 metabotropic glutamate receptor antagonist, or a pharmaceutically acceptable salt thereof.SELECTED DRAWING : NoneCOPYRIGHT : (C)2019, JPO&INPIT