A LIDAR 1 includes: a scanner 55 that emits outgoing light Lo while changing the outgoing direction thereof; a reflection member 8 that is arranged in a first outgoing direction and reflects the outgoing light Lo; an absorption member 7 that is arranged in a second outgoing direction and absorbs the outgoing light Lo; an APD 41 that receives return light Lr; and a DSP16. The DSP 16 generates replica u representing a component reflected by the absorption member 7 on the basis of output signals of the APD 41 obtained at each time when the outgoing light Lo is emitted in the first outgoing direction and in the second outgoing direction.