PURPOSE: To surely hold an illuminator and freely adjust the height of the device main body by screwing a suspension ceiling cap and a support body by a screw and elastically engaging the device main body and the support body.

CONSTITUTION: A suspension ceiling cap 12 is connected to a suspension ceiling 5. A screw part 42 formed around the internal circumference of a support body 13 is threadly screwed to a screw part 35 formed around the circumference face of the suspension ceiling cap 12 in such a state as inserting the suspension ceiling cap 12 into an opening part 31 of a device win body 14. The support body 13 is rotated so as to adjust the height position of the device main body 14 to the ceiling face. A recessed/projecting part 33 of a fitting part 25 formed around the circumference of the opening part 31 of the device main body 14 and a latch part 15 provided in the support body 13 are elastically engaged with each other so as to prevent the support body 13 from rotating in the loosening direction. Fitting of the illuminator is thus facilitated, the device main body 14 is surely secured, its safety is improved.