To provide a form for forming a floor through port, having such advantages that it is unnecessary to use a large amount of wood resources and remove the form for forming the floor through port after concrete is solidified, time and labor for dismantling work are not required, and waste material is not produced.

This form F for forming the floor through port is used to form the floor through port 2 for communication with a lower story on a floor of a building being constructed when concrete 6 is placed on the floor of the building. This form F is provided with a frame body 10 made of reinforcing bars and provided with peripheral wall part skeletons 10A to 10D having shape and size equivalent to a peripheral wall part of the floor through port 2 for communication and a hole drilled steel plate 20 in which small holes 21 to be added to side faces in the peripheral wall skeletons 10A to 10D of the frame body 10 made of reinforcing bars are formed over the whole region.