NOVELTY - An organic semiconductor contains at least one selected from sumanene compound (1), its tautomer, its stereoisomer, and their salts.    USE - As organic transistor material for transistor such as field effect type transistor, thin layer type transistor, electronic devices (all claimed) such as capacitor, battery, organic electroluminescent, fuel cell, organic solar cell.    ADVANTAGE - The organic semiconductor has excellent capability as semiconductor.    DETAILED DESCRIPTION - An organic semiconductor contains at least one selected from sumanene compound of formula (1), its tautomer, its stereoisomer, and their salts.    A1-A6=H, linear or branched alkyl or aromatic hydrocarbon;and    X1-X3=methylene group, vinyldiene group, carbonyl group, thiocarbonyl group, imino methylene group, imino group or oxygen atom.    When the benzyl position hydrogen atom exists on A1-A6, the hydrogen atom is optionally substituted by substituent (A) which is halogen, linear or branched low molecular or polymer chain (optionally containing hetero atom, (un)saturated bond, cyclic structure in principal chain and side chain), carbocyclic ring or heterocyclic ring (monocyclic or condensed ring, or (un)saturated), electron donor group or electron attractive group, or substituent bonded to Ar (r=1-6) bond through a covalent bond and optionally forms a carbocyclic ring or heterocyclic ring. When the hydrogen atom exist on X1-X3, the hydrogen atom is optionally substituted by substituent (B) which is halogen, linear or branched low molecular or polymer chain (optionally containing hetero atom, (un)saturated bond, cyclic structure in principal chain and side chain), carbocyclic ring or heterocyclic ring (monocyclic or condensed ring oar (un)saturation), electron donor group or electron attractive group, or substituent bonded to Xa (a=1-3) bond through a covalent bond and optionally forms a carbocyclic ring or heterocyclic ring.    INDEPENDENT CLAIMS are included for the following:    (i) manufacture of organic semiconductor. After dissolving at least one selected from a sumanene compound (1), its tautomer, its stereoisomer, and their salts, in solvent, recrystallization is performed;    (ii) electronic device which contains the organic semiconductor;    (iii) transistor which contains the organic semiconductor;    (iv) sumanene compound (1), its tautomer, its stereoisomer, and their salts;    (v) manufacture of an organic compound, which involves reacting the compound (1) with aldehyde or ketone in presence of an inorganic base and a phase transfer catalysis, so as to convert the methylene group of substituent (X1-X3) into vinyldiene group; and    X1-X3=vinylidene group, and is optionally substituted by phenyl, thienyl and oligo thiophene chain (The substituent is further optionally substituted by electron donating group(s) or electron withdrawing group).