In a semiconductor light-emitting element, an underlayer is composed of a high crystallinity AlN layer having a FWHM in X-ray rocking curve of 90 seconds or below, and a first cladding layer is composed of an n-AlGaN layer. A light-emitting layer is composed of a base layer made of i-GaN and plural island-shaped single crystal portions made of i-AlGaInN isolated in the base layer.