A nitride semiconductor epitaxial wafer includes a growth substrate including a surface for growing a nitride semiconductor thereon, a first structure layer formed on the growth substrate, a dislocation propagation direction changing layer formed on the first structure layer for changing a propagation direction of a dislocation propagated in the first structure layer into a lateral direction, a second structure layer formed on the dislocation propagation direction changing layer, and a buffer layer formed on the second structure layer for changing a propagation direction of a dislocation propagated in the second structure layer.