An object is to provide a technique that improves the power generation performance, while enhancing the strength of a reinforced electrolyte membrane. There is provided a method of manufacturing a reinforced electrolyte membrane that comprises a first reinforcing film on one surface of an electrolyte membrane and a second reinforcing film on the other surface of the electrolyte membrane. The method of manufacturing the reinforced electrolyte membrane comprises (a) process of thermally compressing the first reinforcing film and the second reinforcing film to the electrolyte membrane. In the process (a), a number of times of thermally compressing the second reinforcing film to the electrolyte membrane is less than a number of times of thermally compressing the first reinforcing film to the electrolyte membrane.