An optical-scanning observation device including: a laser output unit that outputs a laser beam a light scanner that radiates the laser beam on an object while scanning a light detector that detects reflected light of the laser beam and a controller that sets a detection delay time on the basis of a propagation delay time from when the laser beam is output from the laser output unit to when the reflected light is detected by the light detector and that controls the laser output unit and the light detector such that the light detector detects the reflected light after the detection delay time has elapsed since the laser beam is output from the laser output unit.
