PURPOSE: To efficiently obtain a carbamic acid ester useful as a production raw material, etc., of urethane in high yield by reacting phenols with urea in a molar ratio of prescribed value or above while removing ammonia from a reaction system.

CONSTITUTION: Phenols such as phenol expressed by formula I (Ar is aromatic) is made to react with urea in a molar ratio of ≥5 while removing ammonia produced as a by-product such as hexane in a reaction liquid from a reaction system to provide the objective compound of formula II.