For the aromatic compounds as petroleum substitute from lignin, lignophenols synthesized from native lignins through the phase-separation process were depolymerized under the mild alkaline condition. Monophenols recovered from alkaline depolymerized softwood and hardwood lignophenol having many guaiacyl aryl coumaran and syringyl aryl coumaran structures remained diphenylmethane type structure by nucleus-exchange method in good yield. And it was confirmed that the high and low molecular weight fraction of alkaline depolymerized lignophenol had the different structural features by nucleus-exchange treatment.