Provided is an amino acid derivative prodrug represented by general formula (I-A) that is a prodrug form of an amino acid derivative which is a group 2 metabotropic glutamate receptor antagonist, or a pharmaceutically acceptable salt thereof. More specifically, provided is an amino acid derivative prodrug represented by general formula (I-A) that is a preventive or therapeutic drug for mood disorders (including depression and bipolar disorder), anxiety disorder, cognitive disorders, developmental disorders, Alzheimer's disease, Parkinson's disease, movement disorders associated with muscular rigidity, sleep disorders, Huntington's chorea, eating disorders, drug dependence, epilepsy, brain infarction, cerebral ischemia, cerebral insufficiency, cerebral edema, spinal cord disorders, head trauma, inflammation and immune- related diseases, and so on.
