PROBLEM TO BE SOLVED: To provide a method for constructing an optical scanning image which is compact and has high resolution.SOLUTION: A change in light receiving quantity obtained from an imaging surface PF is calculated by partially shading the imaging surface PF formed by an optical signal that is obtained by irradiating an object Obj with illumination light, from light, by a light shielding point 20 and by scanning the imaging surface PF or the shading point 20. On the basis of a result of calculation, an image is formed for each point on the imaging surface PF shaded from light by the shading point 20.