Abstract: A nitride semiconductor light emitting device includes a processed substrate (101a) including a groove and a hill formed on a main surface of a nitride semiconductor substrate, a nitride semiconductor underlayer (102) covering the groove and the hill of the processed substrate, and a light emitting device structure having a light emitting layer (106) including a quantum well layer or a quantum well layer and a barrier layer in contact with the quantum well layer between an n type layer (103-105) and a p type layer (107-110) over the nitride semiconductor underlayer. A current-constricting portion of the light emitting device structure is formed above a region more than 1 &mgr;m away from the center of the groove in the width direction and more than 1 &mgr;m away from the center of the hill in the width direction.