A III-
nitride semiconductor laser device is provided with a
laser structure and an
electrode. The
laser structure includes a support base which comprises a hexagonal III-
nitride semiconductor and has a semipolar primary surface, and a
semiconductor region provided on the semipolar primary surface. The
electrode is provided on the semiconductor region. The semiconductor region includes a first cladding layer of a first
conductivity type GaN-based semiconductor, a second cladding layer of a second
conductivity type GaN-based semiconductor, and an
active layer provided between the first cladding layer and the second cladding layer. The laser structure includes first and second fractured faces intersecting with an m-n plane defined by the m-axis of the hexagonal III-
nitride semiconductor and an axis normal to the semipolar primary surface. A laser cavity of the III-nitride semiconductor laser device includes the first and second fractured faces. An
angle ALPHA between the normal axis and the c-axis of the hexagonal III-nitride semiconductor is in the range of not less than 45 degrees and not more than 80 degrees or in the range of not less than 100 degrees and not more than 135 degrees. The laser structure includes a laser
waveguide extending above the semipolar primary surface, and the laser
waveguide extends in a direction of a
waveguide vector directed from one to another of the first and second fractured faces. A c-axis vector indicating a direction of the c-axis of the hexagonal III-nitride semiconductor includes a projected component parallel to the semipolar primary surface and a vertical component parallel to the normal axis. An angle difference between the waveguide vector and the projected component is in the range of not less than −0.5 degrees and not more than +0.5 degrees.