A method of manufacturing a membrane-electrode assembly including an electrolyte membrane and a catalyst layer-formed gas diffusion layer bonded to the electrolyte membrane, the method including: a liquid application step of applying, in the atmosphere, a liquid to only a surface of the catalyst layer before bonding; and a thermocompression bonding step of bonding, to the electrolyte membrane, the catalyst layer-formed gas diffusion layer to which the liquid is applied, by thermocompression bonding. Provided is a method of manufacturing a membrane-electrode assembly including a polymer electrolyte membrane and a catalyst layer-formed gas diffusion layer bonded to the polymer electrolyte membrane, in which the manufacturing method can achieve both the relaxation of thermocompression bonding conditions and the improvement of adhesion between the catalyst layer-formed gas diffusion layer and the electrolyte membrane with high productivity.