PURPOSE: To substantially reduce mandays and enable even a small number of skillful workers to execute a work, regarding a doorsill formed at area where a building floor carpet is laid.

CONSTITUTION: The bottom of a rectangular and cylindrical setting member 25 having an open upper end is directly secured to a floor 21, and the inside of the member 25 is filled with mortar. Also, the upper surface of the mortar is covered from an upper direction with a rectangular and cylindrical doorsill body 35 having a lower open end, and the side 35a of the body 35 is fixed to the side 25b of the member 25. Also, the bottom 25a of the member 25 made of wood having rectangular cross section is directly fixed to the floor 21, and the upper end of the member 25 is concealed from an upper direction with the body 35 having the lower open end. At the same time, the side 35a of the body 35 is fixed to the side 25b of the member 25.