One genus and two species of fusulinids are collected and described from the upper part of the limestone of the Gabsan Formation, Jecheon area, Chungbuk. The identified fusulinids are Profusulinella arta, Profusulinella wangyui and enable to establish the Profusulinella Zone. This zone is able to correlate with the lower part of Profusulinella Zone in Yeongweol coalfield, the Eostaffella subsolana subzone in Samcheog coalfield, the Profusulinella Zone in U.S.A., the Eostaffella subsolana subzone in China and the lower part of the Profusulinella Zone in Japan. The geologic age of the upper part of the limestone of the Gabsan Formation will be the Lower Moscovian. Though any fusulinids are not found from the lower part of the limestone of the Gabsan Formation, the geologic age of the lower part of the Gabsan Formation would be the Bashkirian. Because the lithostratigraphic sequence is very similar to that of the Yobong Formation in Yeongweol coalfield.