An active layer 17 is provided so as to emit light having a light emission wavelength in the range of 440 to 550 nm. A first conduction type gallium nitride-based semiconductor region 13, the active layer 17, and a second conduction type gallium nitride-based semiconductor region 15 are disposed in a predetermined axis Ax direction. The active layer 17 includes a well layer composed of hexagonal InXGa1-XN (0.16≦X≦0.35, X: strained composition), and the indium composition X is represented by a strained composition. The a-plane of the hexagonal InXGa1-XN is aligned in the predetermined axis Ax direction. The thickness of the well layer is in the range of more than 2.5 nm to 10 nm. When the thickness of the well layer is set to 2.5 nm or more, a light emitting device having a light emission wavelength of 440 nm or more can be formed.