A method of producing a pancreatic hormone-producing cell from a pluripotent stem cell or a pancreas tissue stem/precursor cell, the method comprising the steps of: culturing the pluripotent stem cell in the presence of a growth factor belonging to the TGF-β (transforming growth factor β) superfamily, culturing the cell obtained in the step in the presence of FGF (fibroblast growth factor), culturing the cell obtained in the step in the presence of retinoid, culturing the cell obtained in the step in the presence of a γ-secretase inhibitor and culturing the cell obtained in the step in the presence of at least one factor selected from the group consisting of exendin-4, HGF (hepatocyte growth factor), IGF-1 (insulin like growth factor-1) and nicotinamide, wherein at least one of the steps to is a differentiation-inducing process from the pluripotent stem cell or the pancreas tissue stem/precursor cell to the pancreatic hormone-producing cell, and at least one differentiation-inducing promoter selected from to is added to a culture medium in at least one of the steps to: a polypeptide consisting of an amino acid sequence encoded by DNA consisting of the base sequence set forth in SEQ ID NO. 1, a polypeptide consisting of an amino acid sequence having one or several amino acid substitutions, deletions, and/or additions in the amino acid sequence encoded by DNA consisting of the base sequence set forth in SEQ ID NO. 1, and having a differentiation-inducing promotion effect into a pancreatic hormone-producing cell, a culture supernatant of cells into which DNA consisting of the base sequence set forth in SEQ ID NO.1 or DNA hybridizing with DNA consisting of a base sequence complementary to the DNA consisting of the base sequence set forth in SEQ ID NO: 1 under stringent conditions is incorporated as a foreign gene, wherein the DNA hybridizing with DNA consisting of the base sequence complementary to the DNA consisting of the base sequence set forth in SEQ ID NO: 1 encodes a polypeptide having a differentiation-inducing promotion effect into a pancreatic hormone-producing cell. culturing the pluripotent stem cell in the presence of a growth factor belonging to the TGF-β (transforming growth factor β) superfamily, culturing the cell obtained in the step in the presence of FGF (fibroblast growth factor), culturing the cell obtained in the step in the presence of retinoid, culturing the cell obtained in the step in the presence of a γ-secretase inhibitor and culturing the cell obtained in the step in the presence of at least one factor selected from the group consisting of exendin-4, HGF (hepatocyte growth factor), IGF-1 (insulin like growth factor-1) and nicotinamide, a polypeptide consisting of an amino acid sequence encoded by DNA consisting of the base sequence set forth in SEQ ID NO. 1, a polypeptide consisting of an amino acid sequence having one or several amino acid substitutions, deletions, and/or additions in the amino acid sequence encoded by DNA consisting of the base sequence set forth in SEQ ID NO. 1, and having a differentiation-inducing promotion effect into a pancreatic hormone-producing cell, a culture supernatant of cells into which DNA consisting of the base sequence set forth in SEQ ID NO.1 or DNA hybridizing with DNA consisting of a base sequence complementary to the DNA consisting of the base sequence set forth in SEQ ID NO: 1 under stringent conditions is incorporated as a foreign gene, wherein the DNA hybridizing with DNA consisting of the base sequence complementary to the DNA consisting of the base sequence set forth in SEQ ID NO: 1 encodes a polypeptide having a differentiation-inducing promotion effect into a pancreatic hormone-producing cell.