A method for manufacturing a nitride semiconductor device, includes forming a p-type nitride semiconductor layer on a substrate, from an organic metal compound as a group III element source material, ammonia and a hydrazine derivative as group V element source materials, and a Mg source material gas as a p-type impurity source material. The flow velocity of the source material gases including the group III element source material, the group V element source materials, and the p-type impurity source material is more than 0.2 m/sec.