A composite growth-assisting substrate 10 is formed by epitaxially growing a separation-assisting compound semiconductor layer 10k composed of a non-GaAs III-V compound semiconductor single crystal, and then a sub-substrate 10e composed of a GaAs single crystal in this order, on a first main surface of a substrate bulk 10m composed of a GaAs single crystal. The sub-substrate portion 10e is then separated from the composite growth-assisting substrate 10, so as to be left as a residual substrate portion 1 on a second main surface of the main compound semiconductor layer 40, and a portion of the residual substrate portion 1 is cut off to thereby form a cut-off portion 1j having a bottom surface used as a light extraction surface. By this configuration, the light emitting device is provided as allowing effective use of the GaAs substrate, and increasing the light extraction efficiency.