To provide a molding die which is capable of molding an aluminum cup by easily using a commercial grade aluminum foil.

This molding die 11 for an aluminum cup has a recessed die 13 and a projecting die 15 for molding the aluminum cup using an aluminum foil. The recessed die 13 has a bottom face part 17 and a lateral face part 19 formed by extending all around the entire circumference of the die rising upward from the bottom face part 17. In addition, the lateral face part 19 has an inner face side of such a corrugated cross section that almost equal corrugations are formed over the entire circumference of the recessed die 13 on a horizontal cross section. On the other hand, the projecting die 15 has a bottom part and a lateral part 29, and also has a corrugated cross section 33 formed all around the entire circumference of the die 15 on a horizontal cross section so that the projecting die 15 can fit into the recessed die 13. When the projecting die 15 is fitted into the recessed die 13 through the aluminum foil, the aluminum foil can be out in the upper end part 25a of the lateral face part 19 of the recessed die 13.