There is provided a nitride semiconductor light emitting device in which a semiconductor layer is not broken easily even when a reverse voltage is applied or even in long time operation, and excellent reliability is obtained, by preventing semiconductor layers from deterioration when manufacturing a device. On a surface of a substrate (1), a semiconductor lamination portion (6) made of nitride semiconductor, including a first conductivity type layer (p-type layer (5)) and a second conductivity type layer (n-type layer (3)), is formed, a p-side electrode (8) is provided through a light transmitting conductive layer (7) thereon electrically connected to the p-type layer (5), and an n-side electrode (9) is provided electrically connected to the n-type layer (3) of the lower layer side of the semiconductor lamination portion(6). A mesa-like semiconductor lamination portion (6a) is formed by removing a part of the semiconductor lamination portion (6) around a chip by etching, and the mesa-like semiconductor lamination portion (6a) is formed such that a corner part having an angle of 90 degrees or less is rounded and has a curved line in a plan shape, thereby not to have an angle of 90 degrees or less on corner parts.