In accordance with an embodiment, a manufacturing method of a semiconductor device includes: forming memory cells and select transistors on a semiconductor substrate configured to select any memory cell, forming a first insulating nitride film, forming a contact, and selectively removing the first insulating nitride film. The first insulating nitride film is formed so as to cover the semiconductor substrate between the select transistors adjacent in the first direction, the select transistors, and the memory cells. The first insulating nitride film is selectively removed in a region other than the region in which the contact is formed and in a region above the select transistors or the memory cells.