To obtain an aromatic isocyanate by synthesizing an aromatic urethane by reaction between a diaryl carbonate and an aromatic amine by a simple and economical method practicable on an industrial scale and free of drawbacks involved in prior-art production methods followed by carrying out a thermal decomposition reaction of the aromatic urethane.

A method for synthesizing the urethane compound in high yield and selectivity is provided, comprising carrying out a reaction between the diaryl carbonate and the aromatic amine in the presence of a Lewis acid catalyst. The aromatic isocyanate is synthesized by subsequent thermal decomposition of the urethane compound in a diaryl carbonate solvent used in synthesizing the urethane compound.