The present invention provides a compound of formula (I) or a salt thereof, wherein R 1 , R 2 and R 3 are independently selected from the group consisting of hydrogen atom, fluorine atom, chlorine atom, bromine atom, C 1-6 alkyl, C 1-6 alkoxy substituted with fluorine atom, and others R 4 and R 5 are independently selected from the group consisting of hydrogen atom, fluorine atom, chlorine atom, C 1-6 alkyl, C 1-6 alkoxy substituted with fluorine atom, and others R 6 and R 7 are independently selected from the group consisting of hydrogen atom, fluorine atom, methyl, ethyl, hydroxy group, and others and R 8 and R 9 are independently selected from the group consisting of hydrogen atom, C 1-6 alkyl, and others, which is useful as an agent for treating or preventing various types of epilepsy including partial seizures and/or generalized seizures.
