Disclosed is a method for producing a block copolymer which comprises two or more blocks composed of aromatic units having different basic structures from each other and has a high molecular weight, a narrow chain length distribution and a narrow molecular weight distribution. Also disclosed is a block copolymer produced by the method. The method for producing a block copolymer comprises the step of sequentially reacting two or more aromatic compounds which are selected from aromatic compounds represented by a specific general formula and are different in the group Ar, in the presence of a nickel complex containing a phosphine compound represented by a specific general formula or a palladium complex containing a phosphine compound represented by a specific general formula to thereby form blocks comprising the aromatic compounds sequentially, wherein the two or more aromatic compounds are reacted in descending order of parameter of aromatic ring charge.