A method for producing a multimeric protein comprising the steps of: preparing a monomeric protein having an insoluble granular form in cells of a microorganism, the monomeric protein being a fusion protein of a protein having an immunoglobulin fold structure and a different protein or functional fragment thereof that can serve as a subunit structure able to assemble with other said subunit structure(s) by non-covalent bonding to form a protein having a stable multimeric structure; solubilizing the monomeric protein prepared in step with an aqueous solution containing any one of lauroyl glutamic acid and a salt thereof; diluting a solution obtained in step in a buffer containing any one of arginine and an arginine derivative and inorganic or organic acid salts thereof, to lower a concentration of the any one of lauroyl glutamic acid and a salt thereof, wherein the arginine derivative is selected from the group consisting of arginine having an acyl group with 1 to 6 carbon atoms, arginine butyl ester, agmatine, and argininic acid; and replacing a solvent of a solution obtained in step with a buffer, resulting in removal of said lauroyl glutamic acid and/or a salt thereof, using a method selected from the group consisting of column chromatography selected from the group consisting of gel filtration chromatography, ion-exchange chromatography, hydrophobic interaction chromatography, and a combination thereof; ultrafiltration; dialysis; and a combination of two or more of to; thereby to form a multimeric structure of the fusion protein. preparing a monomeric protein having an insoluble granular form in cells of a microorganism, the monomeric protein being a fusion protein of a protein having an immunoglobulin fold structure and a different protein or functional fragment thereof that can serve as a subunit structure able to assemble with other said subunit structure(s) by non-covalent bonding to form a protein having a stable multimeric structure; solubilizing the monomeric protein prepared in step with an aqueous solution containing any one of lauroyl glutamic acid and a salt thereof; diluting a solution obtained in step in a buffer containing any one of arginine and an arginine derivative and inorganic or organic acid salts thereof, to lower a concentration of the any one of lauroyl glutamic acid and a salt thereof, wherein the arginine derivative is selected from the group consisting of arginine having an acyl group with 1 to 6 carbon atoms, arginine butyl ester, agmatine, and argininic acid; and replacing a solvent of a solution obtained in step with a buffer, resulting in removal of said lauroyl glutamic acid and/or a salt thereof, using a method selected from the group consisting of column chromatography selected from the group consisting of gel filtration chromatography, ion-exchange chromatography, hydrophobic interaction chromatography, and a combination thereof; ultrafiltration; dialysis; and a combination of two or more of to; thereby to form a multimeric structure of the fusion protein. column chromatography selected from the group consisting of gel filtration chromatography, ion-exchange chromatography, hydrophobic interaction chromatography, and a combination thereof; ultrafiltration; dialysis; and a combination of two or more of to;