The present invention relates to a novel compound represented by formula [I] or a pharmacologically-permitted salt thereof. This compound, on the basis of the glycine-uptake-inhibiting effect thereof, is useful in the prevention or therapy of disorders such as schizophrenia, Alzheimer's disease, cognitive impairment, dementia, anxiety disorders (generalized anxiety disorder, panic disorder, obsessive-compulsive disorder, social anxiety disorder, posttraumatic stress disorder, specific phobias, acute stress disorder, and the like), depression, drug dependence, seizures, tremors, pain, Parkinson's disease, attention-deficit hyperactivity disorder, bipolar disorder, eating disorders, or sleep disorders.
