PURPOSE: To obtain a carbonaceous sheet consisting of a carbon fiber and fibril like polyacrylonitrile fiber, having excellent electrical conductivity, thermal conductivity and strength and especially suitable for a catalyst carrier for battery.

CONSTITUTION: For example, a carbon fiber (preferably carbon fiber by vapor phase method) is blended with a fibril like polyacrylonitrile fiber, preferably of 20-50wt.% and the blend is dispersed into water and sufficiently blended by a mixer, etc., and subjected to paper making, etc., to provide the carbonaceous fiber sheet. Furthermore, the carbonaceous fiber sheet is preferably subjected to carbonization treatment at ≥1000°C and graphitization treatment at ≥2500°C so as to improve the strength.