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 R1 and R2, which may be the same or different, each represent C1-C6 alkyl or C3-C8 cycloalkyl, or R1 and R2 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 C1-C6 alkyl), n represents an integer of 0 to 2, T represents a hydrogen atom, halogen or C1-C6 alkyl, and R represents formula (I): or the like}.