Disclosed is a method of manufacturing a semiconductor device, including: forming a stacked structure including first material layers and second material layers alternately stacked on each other; forming a pillar passing through the stacked structure, the pillar including a protruding portion protruding above an uppermost surface of the stacked structure; forming a conductive layer surrounding the protruding portion of the pillar; and forming a conductive pattern in contact with the protruding portion of the pillar by oxidizing a surface of the conductive layer.