The invention provides a Group III nitride semiconductor light-emitting device which has a light extraction face at the n-layer side and which provides high light emission efficiency. The light-emitting device is produced through the laser lift-off technique. The surface of the n-GaN layer of the light-emitting device is roughened. On the n-GaN layer, a transparent film is formed. The transparent film satisfies the following relationship: 0.28≦n×d1×2/λ≦0.42 or 0.63≦n×d1×2/λ≦0.77, wherein n represents the refractive index of the transparent film, d1 represents the thickness of the transparent film in the direction orthogonal to an inclined face thereof, and λ represents the wavelength of the light emitted from the MQW layer.