The present invention provides a synthesis system that can synthesize aniline and/or styrene efficiently, a synthesis system that can synthesize butadiene (1,3-butadiene) efficiently, a rubber chemical for a tire which is synthesized from the aniline obtained by the synthesis system, a synthetic rubber for a tire which is synthesized from the styrene and/or butadiene obtained by the synthesis systems, and a pneumatic tire produced using the rubber chemical for a tire and/or the synthetic rubber for a tire. The present invention relates to a synthesis system for synthesizing aniline and/or styrene from an alcohol having two or more carbon atoms via an aromatic compound.