To efficiently chamfer an opening inner peripheral edge of many small through holes in a perforated floor panel.

The perforated floor panel is composed of a metal made floor panel main body 2 and a finished material 4 which is laminated on a surface 3 of the floor panel main body 2. Chamfered parts 14 are formed by plastic deformation in the opening inner peripheral edge of a finished material side of many small through holes 6 which penetrate an upper surface wall part 5 of the floor panel main body 2 and the finished material 4. When a chamfering dimension of the chamfered parts 14 is shown by B, the chamfering dimension is set at 0.5 mm≤B≤< 2.0 mm.