An optical scanning observation system includes: a light-guide that guides illumination light； an actuator that causes the end portion of the light-guide to oscillate, to thereby be capable of shifting an irradiation position of the illumination light emitted to an object； a light detection section that generates a light detection signal based on return light from the object, and output the generated light detection signal； an error angle acquisition section that acquires an error angle indicating a degree of deviation of the irradiation position of the illumination light； and an image generation section that generates a rotated image by rotating pixel information acquired by converting the light detection signal outputted from the light detection section by an angle acquired by subtracting the error angle from a desired angle of rotation.
