The present invention provides a prophylactic or therapeutic agent for dementia, Alzheimer's disease, attention-deficit hyperactivity disorder, schizophrenia, eating disorders, obesity, diabetes, hyperlipidemia, sleep disorders, narcolepsy, sleep apnea syndrome, circadian rhythm disorder, depression, allergic rhinitis or other diseases.A dihydroquinolinone derivative represented by formula (1) or a pharmaceutically acceptable salt thereof:{wherein Q represents the following formula (A) or (B)}
