The problem to be addressed by the present invention is to provide improved recombinant FcγRIIb and FcγRIIa that do not require refolding and exhibit high productivity and thermal stability, and to provide a method for producing the same. Said problem is solved by improved recombinant FcγRIIb comprising at least the amino acid residues of the extracellular domain of human FcγRIIb (No. 43 to No. 215 in UniProt No. P31994), wherein, in said amino acid residues, at least one amino acid substitution has occurred at a position corresponding to No. 82, 94, 98, 104, 105, or 139 in UniProt No. P31994. Said problem is also solved by improved recombinant FcγRIIa comprising at least the amino acid residues of the extracellular domain of human FcγRIIa (No. 34 to No. 206 in UniProt No. P12318-1), wherein, in said amino acid residues, at least one amino acid substitution has occurred at a position corresponding to No. 73, 85, 89, 95, 96, or 130 in UniProt No. P12318-1.