According to one embodiment, a second electrode layer is formed on first structures where a first electrode layer and a first memory cell layer sequentially stacked above a substrate are patterned in a line-and-space shape extending in a first direction and a first interlayer insulating film embedded between the first structures. Etching is performed from the second electrode layer to a predetermined position in an inner portion of the first memory cell layer by using a first mask layer having a line-and-space pattern extending in a second direction, so that a first trench is formed. A first modifying film is formed on a side surface of the first trench, anisotropic etching is performed on the first memory cell layer by using the first mask layer, and after that, isotropic etching is performed.