In this embodiment, a mask material is formed above a film to be processed, and a plurality of sacrifice films are formed above the mask material, each of the sacrifice films having a columnar shape. Then, a sidewall film is formed on a sidewall of the sacrifice films, and then the sacrifice films are removed. Thereafter, the sidewall films are caused to flow. In addition, a plurality of holes are formed in the mask material using the sidewall film as a mask. Then, isotropic etching is performed for the mask material to etch back the sidewall of the mask material with respect to a sidewall of the sidewall film by a first distance. Thereafter, a deposition layer is deposited inside the plurality of holes to close an opening of the plurality of holes with the deposition layer. Anisotropic etching is conducted to remove the deposition layer in the opening.