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 phenylpyrazole derivative represented by formula (1) or a pharmaceutically acceptable salt thereof: {wherein R 1 and R 2 , which may be the same or different, each represent C 1 -C 6 alkyl or C 3 -C 8 cycloalkyl, or R 1 and R 2 are attached to each other together with their adjacent nitrogen atom to form a 4- to 7-membered saturated heterocyclic ring (wherein said saturated heterocyclic ring may be substituted with halogen or C 1 -C 6 alkyl), n represents an integer of 0 to 2, T represents a hydrogen atom, halogen or C 1 -C 6 alkyl, and R represents formula (I): or the like}.
