To provide a pressing die unit having an excellent press formability capable of further restraining a reduction of the plate thickness excellent in slidability of a cut steel plate.

The pressing die unit is provided with an upper die 1 which forms No.1 plate pressing surface of the opening outer peripheral surface of a forming concavo portion 2, a lower die 2 forming a cut steel plate W by cooperating with the forming concavo portion 2, and a plate pressing member surface 7 having No.2 plate pressing surface 6 which sandwiches the cut steel plate at the pressing conditions between No.1 plate pressing surface 5 and No.2 plate pressing surface 6, allowing the cut steel plat to flow into the forming concavo portion 2 at the time of forming the cut steel plate. At least one of No.1 plate pressing surface 5 or No.2 plate pressing surface 6 is a rough surface having a plurality of striation-like projections, whose striation direction is shaped within ±25 degrees against a peripheral direction of the opening edge of the forming concavo portion 2 or preferably in parallel substantially.