PURPOSE: To provide a fixing metal for a mercury lamp fixing the mercury lamp used for the night illumination at a construction work site to the single pipe of a work scaffold, compactly integrating the mercury lamp and a ballast, simplifying the fitting work at a high location, and serving as a stable fixing means.

CONSTITUTION: A flat plate 2 bent into an L-shape is provided with a connecting means 5 removably coupled with the tip section of a single pipe 4 arranged in the perpendicular direction to the horizontal plane 3 of the flat plate 2 and a fixing means 7 fixing the holder of a mercury lamp. The vertical face 8 of the flat plate 2 is provided with fitting means 10, 11, 19 fitting a ballast and hooking means 16, 17 hooked on the single pipe 4 arranged in the horizontal direction.