In a method for forming a planar microlens according to the present invention, a wet etching is conducted to a glass substrate for a stamper while it is covered with a mask. After the etching is conducted and the mask is removed a wet etching is conducted again to the glass substrate to form densely arranged concave portions thereon, and thereby a stamper is obtained. An uncured resin is applied on the forming surface of the stamper, a glass substrate for a planar microlens array (MLA) is pressed thereto, and thereby the uncured resin is formed. The uncured resin is cured by applying an ultraviolet irradiation thereto and the stamper is released therefrom. The resin layer is removed by a reactive ion etching and whereupon the substrate is etched in a form corresponding to the form of the resin layer and whereby an all-glass microlens of high precision is obtained.