The present invention provides a method for producing a multimeric protein composed of a monomeric protein, wherein the monomeric protein is obtained by fusing a protein having an immunoglobulin fold structure to a protein that can serve as a subunit structure, the method including the steps of: (A) preparing the monomeric protein having an insoluble granular form in cells of a microorganism; (B) solubilizing the monomeric protein prepared in step (A) with an aqueous solution containing lauroyl-L-Glu; (C) diluting a solution obtained in step (B) in a buffer containing arginine hydrochloride to lower a concentration of lauroyl-L-Glu; and (D) replacing a solvent of a solution obtained in step (C) with a buffer using gel filtration chromatography or the like.