To fix a hanging bolt of a luminaire directly to a channel material to be mounted with a ceiling material.

This fixture has both raised parts 111 on an open side 112 and a female screw hole 3 to be screwed in with a hanging bolt 180 of a luminaire 170 which is assembled to a channel material 110' by being thrust from the open side 112 to the channel material 110' having an inwardly folded part 114 at the rim of the raised part 111 and is inserted through the bottom plate part 113 and the ceiling material 160 of the channel material 110'. It also has a projecting engagement part 1 which elastically transforms when thrusting it into the channel material 110' and is engaged with the folded part 114 of the channel material 110' at a designated thrusting position and an abutting surface 2 abutting on the upper end 111a of the raised part 111 of the channel material 111' with the projecting engagement part 1 engaged with the folded part 114 of the channel material 110'.