A group III-nitride laminated substrate includes a sapphire substrate, a first layer that is formed on the sapphire substrate and is made of aluminum nitride, a second layer that is formed on the first layer and serves as an n-type layer made of gallium nitride and doped with an n-type dopant, a third layer that is formed on the second layer and serves as a light-emitting layer made of a group III-nitride, and a fourth layer that is formed on the third layer and serves as a p-type layer made of a group III-nitride and doped with a p-type dopant. The second layer has a thickness of 7 μm or less. A half-value width of (0002) diffraction determined through X-ray rocking curve analysis is 100 seconds or less, and a half-value width of (10-12) diffraction determined through X-ray rocking curve analysis is 200 seconds or less.