To block the motion of a door and to keep the door at its position by allowing an attraction piece to be magnetically held by the permanent mag net of a door metal in a floor metal for a door stop metal fitted to the flap door.

This floor metal is constituted of an upper plate and a lower structural body, and the upper plate is provided with a rectangular window nearly at the center. The lower structural body is constituted of a lower plate, a fixed shaft tube formed by notching and winding the lower plate upward, and the attraction piece made of a magnetic metal plate and rotatably fitted to the fixed shaft tube. The attraction piece is wound downward on one side into a rotary shaft tube, and the rotary shaft tube is rotatably fitted to the fixed shaft tube of the lower plate. The upper plate is overlapped on the lower structural body thus assembled, the attraction piece of the lower structural body is coupled with the window of the upper plate and exposed to the outside in this floor metal for the magnetic door stop metal.