unique effect can be obtained by the use of this kind of pitch exhibiting the anisotropy in summary of the foregoing explanations there can be present carbon precursors having stable fluidity with the viscosity of from 0 4 to 700 poises at a temperature below the thermal decomposition temperature as seen in a few instances as already stated in the foregoing and at the same time exhibiting anisotropy which can be recognized by observation through the polarization microscope after cooling of the substance use of such substances as the raw material is the fundamental concept of the present invention such raw material is shaped into fibers or film by the ordinary methods when manufacturing the carbon fibers melt spinning method is advantageous and other methods such as extrusion compression centrifugal method spray and the like methods can all be used effectively in the case of the film forming the casting process which is generally practiced is employed the infusibilization treatment after shaping as is the case with the pitch fibers is carried out in an oxidizing atmosphere such as ozone oxygen oxides of nitrogen halogens and sulfur trioxides so 3 or an atmosphere containing therein one or more kinds of these gases or in sulfur vapor contact treatment of the pitch fibers after the oxidation treatment with ammonia gas not only accelerates the infusibilization but also improves the carbonization yield and the mechanical strength.