To provide a glare protection device for a floodlight developed so as to reliably illuminate a worksite at night, etc., without dazzling a driver in a running car.

The glare protection device A diffuses and mitigates the glare of the light 3 of an existing floodlight B provided on the top of a telescopic strut 17 standing from a bogie 16 equipped with a power generator 14. A glare protection device A is detachably-installed in front of the light 3. It comprises a device body 1 wherein a glare protection filter 5 is set up on a collapsible and freely-openable/closable umbrella-framed base 4, and a ring-shaped mounting plate 2 provided in front of the light 3 to detachably support the base 4. A retaining hole 14 is opened at a certain interval along the ring direction on the mounting plate 2. Then a released retaining section 13 of the base 4 is inserted into this retaining hole 14 to be locked, allowing the opened umbrella device body 1 to freely be retained detachably in a fixed form in front of the light 3.