Led light emitting device, and lens for led light emitting device

Provided are: a lens for an LED light emitting device having light distribution characteristics suitable for auxiliary light for image pickup, while having a low-cost configuration; and an LED light emitting device using the lens. Emission light outputted from the output surface of a lens (10), said emission light having been emitted from an LED light source (20), is radiated in a rectangular shape on a screen at a predetermined distance from the lens (10), and satisfies formula (1) L2/L1≥0.3, where L1 is center illuminance of the rectangular radiation range, and L2 is illuminance at the four corners of the rectangular radiation range.