A method of producing a thickened carbonated beverage packed in a container, the method comprising: dissolving a first thickening agent which is soluble in water having a temperature of 0 to 35°C in water having a temperature of 0 to 35°C equal to or higher than the temperature at which the first thickening agent can dissolve, thereby obtaining an aqueous solution containing the first thickening agent and having a temperature of 0 to 35°C, wherein the aqueous solution containing the first thickening agent has a viscosity of 20 to 150 [mPa·s] when measured by an E-type viscometer according to JIS Z8803: 2011 under conditions of a temperature of 20°C and a shear rate of 50/s; mixing the aqueous solution containing the first thickening agent and having a temperature of 0 to 35°C with a second thickening agent which is insoluble in water in a temperature range of 0 to 35°C but soluble in water at a temperature of 60°C or more, thereby obtaining a stock liquid in which the second thickening agent is dispersed in the aqueous solution, wherein the stock liquid has a viscosity of 20 to 150 [mPa·s] when measured by an E-type viscometer according to JIS Z8803: 2011 under conditions of a temperature of 20°C and a shear rate of 50/s; dissolving carbon dioxide gas in the stock liquid, thereby obtaining a carbonated aqueous solution; filling a container with the carbonated aqueous solution and sealing the container, thereby obtaining the carbonated aqueous solution packed in the container; and heating the carbonated aqueous solution packed in the container such that the carbonated aqueous solution has a temperature of 60°C or more, thereby dissolving the second thickening agent in the carbonated aqueous solution. dissolving a first thickening agent which is soluble in water having a temperature of 0 to 35°C in water having a temperature of 0 to 35°C equal to or higher than the temperature at which the first thickening agent can dissolve, thereby obtaining an aqueous solution containing the first thickening agent and having a temperature of 0 to 35°C, wherein the aqueous solution containing the first thickening agent has a viscosity of 20 to 150 [mPa·s] when measured by an E-type viscometer according to JIS Z8803: 2011 under conditions of a temperature of 20°C and a shear rate of 50/s; mixing the aqueous solution containing the first thickening agent and having a temperature of 0 to 35°C with a second thickening agent which is insoluble in water in a temperature range of 0 to 35°C but soluble in water at a temperature of 60°C or more, thereby obtaining a stock liquid in which the second thickening agent is dispersed in the aqueous solution, wherein the stock liquid has a viscosity of 20 to 150 [mPa·s] when measured by an E-type viscometer according to JIS Z8803: 2011 under conditions of a temperature of 20°C and a shear rate of 50/s; dissolving carbon dioxide gas in the stock liquid, thereby obtaining a carbonated aqueous solution; filling a container with the carbonated aqueous solution and sealing the container, thereby obtaining the carbonated aqueous solution packed in the container; and heating the carbonated aqueous solution packed in the container such that the carbonated aqueous solution has a temperature of 60°C or more, thereby dissolving the second thickening agent in the carbonated aqueous solution.