A III-nitride semiconductor laser device includes a laser structure including a support base, a semiconductor region, and an electrode. The support base includes a hexagonal III-nitride semiconductor and a semipolar primary surface. The semiconductor region includes first and second cladding layers and an active layer arranged along an axis normal to the semipolar primary surface. A c-axis of the hexagonal III-nitride semiconductor is inclined at an angle ALPHA with respect to the normal axis toward an m-axis of the hexagonal III-nitride semiconductor. The laser structure includes first and second fractured faces that intersect with an m-n plane defined by the normal axis and the m-axis of the hexagonal III-nitride semiconductor. A laser cavity of the laser device includes the first and second fractured faces. Each of the first and second fractured faces have a stripe structure on an end face of the support base.