Method for producing Iii nitride semiconductor device and iii nitride semiconductor device

A laser diode 300 includes a p-type GaN guide layer 107, a current confinement layer 314 provided on the p-type GaN guide layer 107 and having an opening 314A formed therein, and a p-type cladding layer 108 provided on the current confinement layer 314 and plugging the opening 314A formed in the current confinement layer 314. An interface between the p-type cladding layer 108 and the p-type GaN guide layer 107 is located in a bottom of the opening 314A. The current confinement layer 314 is a layer of a group III nitride semiconductor, and a width dimension of the opening 314A is minimized in the upper side of the opening 314A.