Novel indansulfamide derivatives or a pharmaceutically acceptable salt thereof such as N -[(1 S )-2,2,5,7-tetrafluoro-2,3-dihydro-1 H -inden-1-yl]sulfamide, N -[(1S)-2,2,4,7-tetrafluoro-2,3-dihydro-1 H -inden-1-yl]sulfamide, (+)- N -(2,2,4,6,7-pentafluoro-2,3-dihydro-1 H -inden-1-yl)sulfamide, have an action of improving Seizure Severity Index (Score) in mice kindling model. Thus the compounds or the salt thereof are expected as a drug for treating epilepsy.N-[(1S)-2,2,5,7-四氟-2,3-二氫-1H-茚-1-基]磺醯胺、N-[(1S)-2,2,4,7-四氟-2,3-二氫-1H-茚-1-基]磺醯胺、(+)-N-(2,2,4,6,7-五氟-2,3-二氫-1H-茚-1-基)磺醯胺等新穎二氫茚磺醯胺化合物或其藥劑學上所容許之鹽於小鼠點燃模型中具有發作重症度(評分)之改善作用,因此可期待作為癲癇治療劑。