A laser radar device comprising: a modulated light beam generator configured to emit light beams to a detection target, the modulated light beam generator including a light source and a coupling lens; a photodetector configured to receive reflected light which is reflected by the detection target, when the light beams emitted by the modulated light beam generator irradiate the detection target; a reflected light condenser configured to condense the reflected light and configured to guide the reflected light to the photodetector; a single rotator configured to rotate around a rotation axis, including at least two mirrors (3a-3d) configured to scan the light beams in a horizontal direction, and configured to guide the reflected light to the reflected light condenser, the mirrors (3a-3d) including corresponding mirror surfaces tilted by corresponding tilt angles relative to the rotation axis, the tilt angles being different from each other, wherein an angular detection range in a vertical direction relative to a direction in which the light beams are emitted is divided into a plurality of layers; wherein the mirrors (3a-3d) are arranged such that only a light component which is reflected along an optical path which is the same as that of the light beams emitted from the laser radar device enters each mirror again; characterized in that: the modulated light beam generator emits two or more light beams arranged in the vertical direction, the two or more light beams being emitted from the light beam generator at different emission angles, such that each of the two or more light beams is arranged to irradiate the same mirror of the mirrors (3a-3d) as the rotator rotates, wherein a difference between the emission angles corresponds to the angular detection range of one layer in the vertical direction, and wherein emission timings of the light beams are different from each other. a modulated light beam generator configured to emit light beams to a detection target, the modulated light beam generator including a light source and a coupling lens; a photodetector configured to receive reflected light which is reflected by the detection target, when the light beams emitted by the modulated light beam generator irradiate the detection target; a reflected light condenser configured to condense the reflected light and configured to guide the reflected light to the photodetector; a single rotator configured to rotate around a rotation axis, including at least two mirrors (3a-3d) configured to scan the light beams in a horizontal direction, and configured to guide the reflected light to the reflected light condenser, the mirrors (3a-3d) including corresponding mirror surfaces tilted by corresponding tilt angles relative to the rotation axis, the tilt angles being different from each other, wherein an angular detection range in a vertical direction relative to a direction in which the light beams are emitted is divided into a plurality of layers; wherein the mirrors (3a-3d) are arranged such that only a light component which is reflected along an optical path which is the same as that of the light beams emitted from the laser radar device enters each mirror again; the modulated light beam generator emits two or more light beams arranged in the vertical direction, the two or more light beams being emitted from the light beam generator at different emission angles, such that each of the two or more light beams is arranged to irradiate the same mirror of the mirrors (3a-3d) as the rotator rotates, wherein a difference between the emission angles corresponds to the angular detection range of one layer in the vertical direction, and wherein emission timings of the light beams are different from each other.