To provide a method of manufacturing a mold body for forming a nanostructure having excellent optical characteristics such as light antireflection performance, light transparency and haze and remarkably reduced in waving and point defects.

The method of manufacturing the mold body for forming the nanostructure is provided by which tapered fine pores are formed on the surface of an aluminum material by the combination of anodic oxidation and the etching of the anodic oxidation film after the surface of the aluminum material is electrolytically polished. The electrolyte of the electrolytic polishing is prepared by blending ≥40 pts. vol. and ≤75 pts.vol. of a concentrated phosphoric acid, ≥10 pts.vol. and ≤55 pts.vol. of a concentrated sulfuric acid and ≥5 pts.vol. and ≤25 pts.vol. of water to be blended, wherein the volume of a concentrated sulfuric acid is made larger than that of water.