A method for collecting a compound of general formula from a liquid phase component that is formed as a by-product in a method for producing a compound of general formula, comprising: step: a step for reacting the liquid phase component with at least one active hydrogen-containing compound in a reactor while extracting at least a partial amount of gas phase components formed in step to an outside of the reactor, wherein the gas phase components are extracted continuously so as to allow the decomposition reaction in which the pressure is maintained within a certain range to proceed promptly, and wherein the gas phase components are extracted from the reactor, without extracting the active hydrogen containing compound together with the gas phase components to the outside of the reactor, or while controlling the pressure inside the reactor by disposing a pressure-holding valve configured to control the pressure; step: a step for introducing the gas phase components extracted from the reactor into a condenser connected with the reactor to conduct cooling, and returning a condensed liquid obtained by the cooling to the reactor; step: a step for discharging gas phase components that are not condensed in the step to an outside of the reactor; and step: a step for discharging, as a liquid phase component inside the reactor, a reaction liquid formed in step and containing the compound of general formula to the outside of the reactor, in the general formula, R 11 represents a monovalent to trivalent organic group, and n11 represents an integer of 1 to 3, and in the general formula, R 31 represents a monovalent to trivalent organic group, and n31 represents an integer of 1 to 3, wherein the liquid phase component that is formed as a by-product in the method for producing the compound of general formula is a liquid phase component extracted from a thermal decomposition reactor when gas phase components comprising the compound of general formula generated by supplying a liquid containing a carbamate produced from a carbonic acid derivative, a hydroxy compound and the compound of general formula to the thermal decomposition reactor and then subjecting the carbamate to thermal decomposition reaction is collected, wherein the gas phase components formed in step have a boiling point lower than that of the liquid phase component formed as a by-product in the method for producing the compound of general formula or the active hydrogen-containing compound which are raw materials in step, wherein the active hydrogen-containing compound is selected from the group consisting of water, urea, alcohols, aromatic hydroxy compounds and organic primary amines, wherein at least one of the active hydrogen-containing compound is water, and the gas phase component discharged in step comprises carbon dioxide, and wherein the carbonic acid derivative is urea or a carbonic acid ester. step: a step for reacting the liquid phase component with at least one active hydrogen-containing compound in a reactor while extracting at least a partial amount of gas phase components formed in step to an outside of the reactor, wherein the gas phase components are extracted continuously so as to allow the decomposition reaction in which the pressure is maintained within a certain range to proceed promptly, and wherein the gas phase components are extracted from the reactor, without extracting the active hydrogen containing compound together with the gas phase components to the outside of the reactor, or while controlling the pressure inside the reactor by disposing a pressure-holding valve configured to control the pressure; step: a step for introducing the gas phase components extracted from the reactor into a condenser connected with the reactor to conduct cooling, and returning a condensed liquid obtained by the cooling to the reactor; step: a step for discharging gas phase components that are not condensed in the step to an outside of the reactor; and step: a step for discharging, as a liquid phase component inside the reactor, a reaction liquid formed in step and containing the compound of general formula to the outside of the reactor, in the general formula, R 11 represents a monovalent to trivalent organic group, and n11 represents an integer of 1 to 3, and in the general formula, R 31 represents a monovalent to trivalent organic group, and n31 represents an integer of 1 to 3, wherein the liquid phase component that is formed as a by-product in the method for producing the compound of general formula is a liquid phase component extracted from a thermal decomposition reactor when gas phase components comprising the compound of general formula generated by supplying a liquid containing a carbamate produced from a carbonic acid derivative, a hydroxy compound and the compound of general formula to the thermal decomposition reactor and then subjecting the carbamate to thermal decomposition reaction is collected, wherein the gas phase components formed in step have a boiling point lower than that of the liquid phase component formed as a by-product in the method for producing the compound of general formula or the active hydrogen-containing compound which are raw materials in step, wherein the active hydrogen-containing compound is selected from the group consisting of water, urea, alcohols, aromatic hydroxy compounds and organic primary amines, wherein at least one of the active hydrogen-containing compound is water, and the gas phase component discharged in step comprises carbon dioxide, and wherein the carbonic acid derivative is urea or a carbonic acid ester.