Method of producing fuel cell

A method of manufacturing a fuel cell comprising:

• a catalyst layer forming step of applying ink containing an anode catalyst to one surface of an electrolyte membrane, and applying ink containing a cathode catalyst to another surface of the electrolyte membrane, and then firing the electrolyte membrane to form an anode catalyst layer and a cathode catalyst layer on the electrolyte membrane;
• an anode diffusion layer stacking step of stacking an anode diffusion layer on the anode catalyst layer;
• a cathode diffusion layer stacking step of stacking a cathode diffusion layer on the cathode catalyst layer;
• a membrane electrode assembly forming step of forming a membrane electrode assembly by pressing and heating, using a pressurizing device, a stacked structure formed of the anode diffusion layer, the anode catalyst layer, the electrolyte membrane, the cathode catalyst layer, the cathode diffusion layer, to form the membrane electrode assembly including a joining interface layer formed between the gas diffusion layer and the catalyst layer, the joining interface layer containing a solid electrolyte;
• a preliminary treatment step of bringing superheated steam into contact with the membrane electrode assembly thereby increasing porosity of the joining interface layer without pressing the membrane electrode assembly;
• and
• an aging step of applying a voltage having a predetermined waveform between an anode electrode and a cathode electrode of the membrane electrode assembly subjected to the preliminary treatment step.