Provided is a manufacturing method of a nitride semiconductor device having a nitride semiconductor substrate (e.g. GaN substrate) in which dislocation concentrated regions align in stripe formation, the dislocation concentrated regions extending from a front surface to a back surface of the substrate, the manufacturing method being for stacking each of a plurality of nitride semiconductor layers on the front surface of the substrate in a constant film thickness. Grooves are formed on the nitride semiconductor substrate in the immediate areas of dislocation concentrated regions. Each of the nitride semiconductor layers is formed as a crystal growth layer on the main surface of the nitride semiconductor substrate to which the grooves have been formed.