An optical scanning endoscope device includes: a light source that emits illumination light； an optical fiber that emits the illumination light from a distal end； an optical scanner that scans the illumination light on a subject； a return-light detector that detects return light returning from the subject； an emitted-light-amount detector that detects an amount of a portion of the illumination light emitted from the distal end； a converter that converts the detected amount of light into an amount of entire illumination light emitted from the distal end； a controller that controls an amount of the illumination light emitted by the light source based on the converted amount of emitted light； and a calculator that calculates an actual amount of the illumination light based on the detected amount of light and the detected amount of return light. The converter converts the actual amount into the amount of entire emitted illumination light.
