The present invention provides: a synthesis system for synthesizing aniline and/or styrene with high efficiency; a synthesis system for synthesizing butadiene (1,3-butadiene) with high efficiency; a rubber chemical substance for tires, which is synthesized using, as a starting material, aniline produced in the aforementioned synthesis system; a synthetic rubber for tires, which is synthesized using, as a starting material, styrene and/or butadiene produced in the aforementioned synthesis system; and a pneumatic tire produced using the rubber chemical substance for tires and/or the synthetic rubber for tires. The present invention relates to a synthesis system for synthesizing aniline and/or styrene through an aromatic compound using an alcohol having 2 or more carbon atoms as a starting material.