The output enhancement of a green InGaN/GaN quantum-well (QW) light-emitting diode(LED) through the coupling of a QW with localized surface plasmons (LSPs), which aregenerated on Ag nanostructures on the top of the device, is demonstrated. Thesuitable Ag nanostructures for generating LSPs of resonance energies aroundthe LED wavelength are formed by controlling the Ag deposition thickness andthe post-thermal-annealing condition. With a 20 mA current injected onto theLED, enhancements of up to 150% in electroluminescence peak intensity andof 120% in integrated intensity are observed. By comparing this with a similarresult for a blue LED previously published, it is confirmed that surface plasmoncoupling for emission enhancement can be more effective for an InGaN/GaN QW oflower crystal quality, which normally corresponds to the emission of a longerwavelength.