TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Component: The two types of fullerenes each having a different molecular weight are 60C fullerene and 70C fullerene. The solvent is benzonitrile. Preferred Compositions: The ratio of solubility of the fullerene showing a relatively high solubility to the solubility of the fullerene showing a relatively low solubility is greater than or equal to 2. The content of fullerene showing a relatively high solubility in the solvent is 0.5-10 mole%. Preferred Property: A fullerene crystal body comprises at least two types of fullerenes each having a different molecular weight is bonded by covalent bond and/or van del Waals' bond. Preferred Condition: The fullerene showing a relatively low solubility is dissolved in advance in a solvent. EXAMPLE - Fullerene 60C (0.1 g) was dissolved in 1,3,5-trimethylbenzene (100 mL), separate fullerene 70C (0.1 g) was dissolved in 1,3,5-trimethylbenzene (100 mL), and resultant fullerene 60C solution (19.5 mL) and fullerene 70C solution were placed in 50 mL lidded bottle and mixed to prepare a mixed fullerene solution. The resultant mixed fullerene solution was cooled to 10 degrees C, 2-butanol (6 mL) which had been cooled to 10 degrees C separately was allowed to slowly flow in mixed fullerene solution to form a liquid-liquid interface, forming a 2-butanol layer in upper portion and the mixed fullerene solution is in lower portion, and the resultant mixture was allowed to stand and preserved in a dark place at 10 degrees C for 60 hours. A large number of fibrous crystals had been deposited in the mixed fullerene solution. The fibrous crystals were taken out through filtration, washed with 2-butanol, heated at 250 degrees C for 2 hours, placed in 5 mL lidded bottle, added benzonitrile (1 mL), and was allowed to stand and preserved in a dark place at 10 degrees C for further 48 hours. The transparent benzonitrile was removed and became brown colored. The fibrous crystals were removed, heated at 200 degrees C for 3 hours to evaporate off the benzonitrile, and obtained porous fibrous crystals. The surface conditions of the carbon fibers before and after the elution treatment were shown with scanning electron microscope micrograph. As a result, pore constitution was recognized to have been formed on the surface of the fullerene crystal along the stretching direction of fibers. The average pore diameter resulted in 500 nm.