NOVELTY - Manufacture of dithienobenzodithiophene derivative (I) involves preparing Grignard reagent of 3-bromo-2-halo-5-substituted-type thiophene, synthesizing 3-bromo-5-substituted-type thiophene-2-zinc derivative from the Grignard reagent, reacting 3-bromo-5-substituted-type thiophene-2-zinc derivative with 1,2,4,5-tetrahalobenzene-1,4-bis(3-bromo-5-substituted-2-thienyl)-2,5-dihalobenzene in the presence of a catalyst, and carrying out intramolecular cyclization of 1,4-bis(3-bromo-5-substituted-2-thienyl)-2,5-dihalobenzene in presence of an alkali sulfide metal salt.    USE - Manufacture of dithienobenzodithiophene derivative e.g. dimethyl dithienobenzodithiophene, di-n-butyl dithienobenzodithiophene, di-n-pentyl dithienobenzodithiophene, di-n-hexyl dithienobenzodithiophene, di-2-ethylhexyl dithienobenzodithiophene, di-n-nonyl dithienobenzodithiophene, di-n-heptyl dithienobenzodithiophene, di-n-octyl dithienobenzodithiophene, di-n-decyl dithienobenzodithiophene, di-n-dodecyl dithienobenzodithiophene, and di-n-tetradecyl dithienobenzodithiophene (all claimed) used for forming organic semiconductor layer for organic semiconductor device e.g. organic thin-film transistor. Uses include but are not limited to organic electroluminescent display, liquid crystal display, radio frequency identification tag, electronic paper, laser, and organic thin-film solar cell.    ADVANTAGE - The method enables efficient manufacture of dithienobenzodithiophene derivative, providing organic semiconductor layer with high carrier mobility, by simple process.    DETAILED DESCRIPTION - Manufacture of dithienobenzodithiophene derivative of formula (I) involves converting 2-bromo-5-substituted-type thiophene into 4-bromo-2-substituted-type thiophene, converting 4-bromo-2-substituted-type thiophene into 3-bromo-2-halo-5-substituted-type thiophene, preparing Grignard reagent of 3-bromo-2-halo-5-substituted-type thiophene, synthesizing 3-bromo-5-substituted-type thiophene-2-zinc derivative from the Grignard reagent, reacting 3-bromo-5-substituted-type thiophene-2-zinc derivative with 1,2,4,5-tetrahalobenzene-1,4-bis(3-bromo-5-substituted-2-thienyl)-2,5-dihalobenzene in the presence of a palladium catalyst, and carrying out intramolecular cyclization of 1,4-bis(3-bromo-5-substituted-2-thienyl)-2,5-dihalobenzene in the presence of an alkali sulfide metal salt.    R1,R2=1-20C alkyl, 2-20C alkenyl, 2-20C alkynyl, 1-20C alkoxy, 1-20C alkylthio, 1-20C haloalkyl, 3-10C cycloalkyl, heteroaryl, or group of formula: -Y'-R3 (iii);    R3=3-10C cycloalkyl, 6-14C aryl, 3-12-membered cycloheteroalkyl, or 5-14-membered heteroaryl;and    Y'=1-6C bivalent alkyl, 1-6C bivalent haloalkyl, 3-12-membered 6-14C aryl, or 5-14-membered cycloheteroalkyl.