To provide a corner cube reflector having a plurality of unit structures arranged at fine pitches, and ensuring excellent retroreflection.

The corner cube array formation method includes steps of: (A) preparing a layer 31 to be etched having a crystal structure; (B) forming a mask layer which is constituted of a plurality of masks 32a and has a pattern for regulating the arrangement of corner cubes on the layer 31 by the use of a material different from that of the layer 31; and (C) providing the layer 31 with a shape 33 for regulating the retroreflection of the corner cube arrays, by etching the layer 31 from the area not covered with masks 32a. The step (C) includes steps of: (C1) obtaining reflected light by emitting light 34 to the areas including the areas where the mask parts 32a of the layer 31 are formed and the areas where the mask parts 32a are not formed; (C2) detecting, on the basis of the reflected light, a point of time when the masks 32a are peeled from the layer 31; and (C3) stopping the etching of the layer 31.