PURPOSE: To easily perform positioning when balcony units are mutually connected.

CONSTITUTION: A room side bracket 100 provided with a horizontal plate part 110 having a pin hole 111 and first and second vertical plate parts 120, 130 is fixed to the side of a building unit 1 through the first vertical plate part 120. Meanwhile, a balcony side bracket 200 provided with a horizontal plate part 210 having a pin 211 on its underside and first and second vertical plate parts 220, 230 is fixed on the end face on the building unit side of the side wall of a balcony unit 3 through the first vertical plate part 220. The horizontal plate part 210 of the balcony side bracket 200 is placed on the horizontal plate part 110 of the room side bracket 100 in the condition of inserting the pin 211 into the pin hole 111. The second vertical plate part 130 of the room side bracket 100 and the second vertical plate part 230 of the balcony side bracket 200 are fastened together and fixed by bolts through both bolt holes 131, 231.