A method for producing an electrode assembly includes: obtaining a porous active material molded body by molding a constituent material containing a lithium multiple oxide in the form of particles by compression, and then performing a heat treatment at a temperature of 850° C. or higher and lower than the melting point of the used lithium multiple oxide; forming a solid electrolyte layer by applying a liquid containing a constituent material of an inorganic solid electrolyte to the surface of the active material molded body including the inside of each pore of the active material molded body, and then performing a heat treatment; and bonding a current collector to the active material molded body exposed from the solid electrolyte layer.