An optical scanning device comprising a transmission or reflection hologram disk, wherein recording beams, such as an object and a reference beam which are used in preparing holograms, and a reconstructing beam which is used in reconstructing or scanning, are spherical waves having different wavelengths; and wherein the sources of recording beams and reconstructing beams are located at different positions for enabling the beams to fall obliquely on the hologram disk to cause a reconstructed image on a focusing or scanning plane to be subjected to linear aberration free scanning. The incident angle of the reconstructing beam on the hologram disk meets the Bragg condition for high diffraction efficiency.