An object of the present invention is to provide a process for producing isocyanates, which are industrially useful compounds, without using phosgene, and to provide a process for chemically recycling waste polycarbonate resin. The present invention discloses a process enabling isocyanate compounds to be produced without using phosgene as a raw material by subjecting a carbamic acid ester compound obtained by a reaction between an aromatic polycarbonate resin and an amine compound to a thermal decomposition reaction, while at the same time disclosing a process enabling chemical recycling of aromatic polycarbonate resin by recovering a divalent aromatic hydroxy compound forming aromatic polycarbonates.