To effectively discharge a lubricant which is supplied into a forming cavity of a sizing die apparatus.

A structure for discharging the lubricant is constituted such that the outside of a base 1 and a reinforcing ring 2 is enclosed by a case 3, an upper insert 4 and a lower insert 5 are arranged separately inside a reinforcing ring 2 which support them firmly from outer periphery, and ten the lubricant oil is discharged outside through a discharge hole 12. The discharge hole 12 comprises a discharge hole 12a, which is formed on the face of a parting phase of the upper insert 4 and lower insert 5, a discharge hole 12b, which is formed on the boundary between an reinforcing ring 2 and a case 3, and a discharge hole 12c, which is drilled in a case 3.