A method for forming many microlenses comparatively easily and effectively is provided. On one end of an optical substrate is formed a plurality of lens planes at regular intervals. Lens areas containing the lens planes are partially covered by an etching mask and etching processing is performed on areas being exposed outside the etching mask to remove the areas to a specified depth. While the lens planes formed on one surface of the optical substrate are being held by a support substrate, polishing processing is performed on another end face of the optical substrate and each microlens formed in the lens areas is separated from the support substrate.