The present invention relates to an LED emergency light installed in a lamp receptacle. The LED emergency light includes a light source unit (30), in which LEDs are mounted on a PCB. In a housing (10), a threaded receptacle coupling unit (11) is provided, and the light source unit is installed. A power connection unit (20) includes switching means (21), connected to the threaded receptacle coupling unit to automatically supply power from a primary cell (40) to the light source unit at a time of a power failure, and ON/OFF control means (25), configured to limit and adjust a time for which current from the primary cell flows through the light source unit. The primary cell is electrically connected to the power connection unit and the light source unit, and turns on the LEDs by supplying power to the light source unit at a time of power failure.