Abstract: A light source unit holder, on which a light source unit is mounted, is rockably supported via a gimbal mechanism, and projects a brightline using a laser beam emitted from the light source unit, the gimbal mechanism includes a pair of shafts that support the rocking body rockably from both sides thereof, a spherical-body receiving hole is formed at a tip of the pair of shafts, and also in the rocking body a spherical-body receiving hole is formed in a position to which the tips of the pair of shafts face, and a spherical body is interposed between the spherical-body receiving hole of the pair of shafts and the spherical-body receiving hole of the rocking body, the latter spherical-body receiving hole facing the spherical-body receiving hole of each shaft, so that the rocking body is rockably supported, for preventing dynamic sensitivity of the gimbal mechanism from decreasing.