To easily bury a foam fire extinguishing facility in a predetermined position in the island of a service station.

A positioning hole part 38 is provided in the center position of the head case mounting position of the concrete form 26 of an island. A mounting fitting 27 is removably mounted in the front end opening 21 of a head case 4 enclosing a foam fire extinguisher releasing head 11. The mounting fitting 27 is removably mounted in the positioning hole part 38 in the inner surface of the concrete form 26 by a mounting bolt 32 and nut 34. A pipeline 7 is connected to the head case 4. Next, the island 1 is molded by placing concrete in the concrete form 26 and at the same time the head case 4 is molded by embedding. After the concrete is cured, the concrete form 26 is removed. The mounting fitting 27 is removed from the head case 4. Finally, a protective cap 23 is mounted in the front end opening 21 of the head case 4 in such a way that it does not protrude from the side face of the island.