A nitride-based semiconductor laser device includes a nitride-based semiconductor layer formed on a main surface of a substrate and having an emission layer, wherein the nitride-based semiconductor layer includes a first side surface formed by a (000-1) plane and a second side surface inclined with respect to the first side surface, and a ridge having an optical waveguide extending perpendicular to a [0001] direction in an in-plane direction of the main surface of the substrate is formed by a region held between the first side surface and the second side surface.