A method for producing an N-substituted carbamic acid ester from an organic amine, a carbonic acid derivative and a hydroxy composition containing one or more types of hydroxy compounds, the method comprising following steps (a) and (b): step (a): a step of obtaining a reaction mixture containing a compound having an ureido group by reacting the organic amine and the carbonic acid derivative; and step (b): a step of producing the N-substituted carbamic acid ester by reacting the compound having the ureido group, which is obtained in the step (a), and the hydroxy composition using a urethane production reaction vessel provided with a condenser, wherein a gas containing the hydroxy composition, the compound having the carbonyl group derived from the carbonic acid derivative and an ammonia produced as a by-product in the reaction is introduced into the condenser provided in the urethane production reaction vessel, and a hydroxy composition and the compound having the carbonyl group derived from the carbonic acid derivative are condensed, wherein the carbonic acid derivative is a compound represented by Formula: wherein X represents an amino group having 0 to 20 carbon atoms, and Y represents an organic group having 1 to 20 carbon atoms or an amino group having 0 to 20 carbon atoms, wherein the one or more hydroxy compounds is an alcohol represented by Formula or an aromatic hydroxy compound represented by Formula: R 20 (̵OH) g wherein R 20 represents a group composed of an aliphatic group having 1 to 50 carbon atoms substituted with g hydroxy groups or an aliphatic group having 7 to 50 carbon atoms to which is bonded an aromatic group, an OH group of the alcohol represented by Formula is an OH group not bonded to an aromatic group, and g represents an integer of 1 to 5, provided that R 20 is a group that does not have an active hydrogen other than that of the hydroxy group, or wherein ring A represents an optionally substituted aromatic hydrocarbon ring and may be monocyclic or polycyclic, R 3 and R 4 respectively and independently represent a hydrogen atom or organic group, the number of carbon atoms that compose the aromatic hydroxy compound is an integer of from 6 to 50, and R 3 and R 4 may bond with A to form a ring structure; and wherein the compound having an ureido group is a compound represented by the Formula: wherein R 1 represents an organic group which has 1 to 85 carbon atoms and which is substituted by h number of ureido groups, and h represents an integer of 1 to 10. step (a): a step of obtaining a reaction mixture containing a compound having an ureido group by reacting the organic amine and the carbonic acid derivative; and step (b): a step of producing the N-substituted carbamic acid ester by reacting the compound having the ureido group, which is obtained in the step (a), and the hydroxy composition using a urethane production reaction vessel provided with a condenser, X represents an amino group having 0 to 20 carbon atoms, and Y represents an organic group having 1 to 20 carbon atoms or an amino group having 0 to 20 carbon atoms, wherein the one or more hydroxy compounds is an alcohol represented by Formula or an aromatic hydroxy compound represented by Formula: R 20 (̵OH) g wherein R 20 represents a group composed of an aliphatic group having 1 to 50 carbon atoms substituted with g hydroxy groups or an aliphatic group having 7 to 50 carbon atoms to which is bonded an aromatic group, an OH group of the alcohol represented by Formula is an OH group not bonded to an aromatic group, and g represents an integer of 1 to 5, provided that R 20 is a group that does not have an active hydrogen other than that of the hydroxy group, or wherein ring A represents an optionally substituted aromatic hydrocarbon ring and may be monocyclic or polycyclic, R 3 and R 4 respectively and independently represent a hydrogen atom or organic group, the number of carbon atoms that compose the aromatic hydroxy compound is an integer of from 6 to 50, and R 3 and R 4 may bond with A to form a ring structure; and R 20 represents a group composed of an aliphatic group having 1 to 50 carbon atoms substituted with g hydroxy groups or an aliphatic group having 7 to 50 carbon atoms to which is bonded an aromatic group, an OH group of the alcohol represented by Formula is an OH group not bonded to an aromatic group, and g represents an integer of 1 to 5, provided that R 20 is a group that does not have an active hydrogen other than that of the hydroxy group, or ring A represents an optionally substituted aromatic hydrocarbon ring and may be monocyclic or polycyclic, R 3 and R 4 respectively and independently represent a hydrogen atom or organic group, the number of carbon atoms that compose the aromatic hydroxy compound is an integer of from 6 to 50, and R 3 and R 4 may bond with A to form a ring structure; wherein the compound having an ureido group is a compound represented by the Formula: wherein R 1 represents an organic group which has 1 to 85 carbon atoms and which is substituted by h number of ureido groups, and h represents an integer of 1 to 10. R 1 represents an organic group which has 1 to 85 carbon atoms and which is substituted by h number of ureido groups, and h represents an integer of 1 to 10.