The present invention relates to a novel compound represented by formula [I] or a pharmaceutically acceptable salt thereof. This compound is useful for the prevention or treatment of diseases such as schizophrenia, Alzheimer's disease, cognitive dysfunction, dementia, anxiety disorders (generalized anxiety disorder, panic disorder, obsessive-compulsive disorder, social anxiety disorder, post-traumatic stress disorder, a specific phobia, acute stress disorder, and the like), depression, drug dependence, convulsion, tremor, pain, Parkinson's disease, attention deficit/hyperactivity disorder, bipolar disorder, eating disorder, sleep disorder and the like, of which the action relies on an inhibitory activity on the intake of glycine.
