A ranging device includes a plurality of ranging units and a control unit configured to control the plurality of ranging units. Each of the ranging units includes a deflection member configured to deflect laser light and performs ranging processing that scans a predetermined ranging area with emitted laser light by rotating or oscillating the deflection member to change the emission azimuth of the laser light, and measures a distance to an object located in the emission azimuth based on reflected light received from the same azimuth as the emission azimuth. The plurality of ranging units include a first ranging unit and a second ranging unit with the ranging areas overlapping with each other. The control unit causes the first ranging unit to perform the ranging processing and the second ranging unit to perform ranging processing in parallel with each other in a manner to prevent the area traveled by laser light emitted by the first ranging unit and the area traveled by laser light emitted by the second ranging unit from interfering with each other in the ranging areas.