To make a structure for preventing cut chips from splashing, even if forming female screws of both of front and rear faces by only tapping from one side without reversing a die-cast frame.

This die cast frame 1 is provided with boss parts 2 having substantially flat shapes and formed with the female screws from each direction on both of the front and rear faces. A prepared hole 3 of tapping passing through the boss part 2 on the rear face side is formed in advance. After forming the female screw passing through the boss part 2 on the rear face side by performing tapping from the bottom face side by the same process as the tapping of the boss part 2 on the front face side which is placed at an upper position, a bottom part opening part of the female screw on the rear face side is closed by punching by a punch 6.