Membrane catalyst layer assembly production method and membrane catalyst layer assembly production device

A membrane catalyst layer assembly production method is provided for producing a membrane catalyst layer assembly by discharging catalyst ink having a solvent and a solid component onto an electrolyte membrane. The membrane catalyst layer assembly production method includes forming a first catalyst ink layer having a first porosity on the electrolyte membrane by controlling a porosity of a catalyst ink layer that is formed by the catalyst ink making impact with the electrolyte membrane by adjusting an amount of solvent in the catalyst ink in drop form prior to impact with the electrolyte membrane, and forming a second catalyst ink layer having a second porosity, which is different from the first porosity, on the first catalyst ink layer, by adjusting the amount of solvent in the catalyst ink in drop form prior to impact with the first catalyst ink layer.