New localities of Arisaema seppikoense Kitam., a critically endangered and endemic species in central parts of Hyogo Prefecture, were recently discovered, and this species was morphologically re-examined. One plant with two foliage leaves was newly found. Male plant usually had less than seven leaflets. The length of pseudostem and peduncle in female plant were significantly longer than those of males. The spathe blade, spadix-appendage and anther showed the various combinations of color. Arisaema seppikoense does not seem to be so closely related to A. cucullatum M. Hotta based on the morphological and cytological differences examined.