A scanning endoscope apparatus includes a light source section that emits illumination light, an optical fiber that irradiates the illumination light from a distal end to a subject with directivity, a drive element and a scanning drive section that perform scanning by the distal end of the optical fiber, a first light detection section that detects light from a direction of the distal end of the optical fiber, a second light detection section that detects light from an entire scanning range, and an image processing section that forms image information to be outputted to a display section based on a result of addition of a detection result corresponding to an external factor light component in a first light detection result and a second light detection result.