A light detection and ranging (lidar) device includes: a lower base; an upper base; a laser emitting unit for emitting a laser in a form of a point light source; a nodding mirror for transforming the laser in the form of the point light source to a line beam pattern which is perpendicular to the lower base, wherein the nodding mirror reflects the laser emitted from the laser emitting unit; a polygonal mirror for transforming the line beam pattern to a plane beam pattern and receiving a laser reflected from an object; and a sensor unit for receiving the laser reflected from the object via the polygonal mirror.