A nitride semiconductor device of high quality and excellent crystallinity and the method of manufacturing the same, wherein a nitride series compound semiconductor having at least an element belonging to the group IIIA and nitrogen is grown directly on a substrate, X-ray diffraction peaks of the nitride series compound semiconductor consist only of the peaks from the C-face of the hexagonal system, and the half width of an X-ray rocking curve at (0002) peak in the C-surface is 0.2 degrees of less, and wherein the method includes a step of introducing an organic metal compound at least containing a group IIIA element and a plasma activated nitrogen source into a reaction vessel to grow a nitride series compound semiconductor on the surface of a substrate, in which the ratio for the amount of the group IIIA element and nitrogen atom supplied (ratio for the number of atoms) is group IIIA element: nitrogen atom=1:50,000 to 1:1,000,000.