Abstract: A nitride semiconductor device includes n-type and p-type nitride semiconductor layers, an active layer, the active layer having a lamination of quantum barrier layers and quantum well layers, a thermal stress control layer disposed between the n-type nitride semiconductor layer and the active layer, and formed of a material having a smaller thermal expansion coefficient than the n-type and p-type nitride semiconductor layers, and a lattice stress control layer disposed between the thermal stress control layer and the active layer, and including a first layer and a second layer.