A method for fabricating a semiconductor device with a buried gate includes: etching a substrate to form a plurality of trenches; forming a plurality of buried gates that fill lower portions of the trenches; forming a plurality of sealing layers that gap-fill upper portions of the trenches and have protrusions higher than a top surface of the substrate; forming an inter-layer insulation layer over the whole surface of the substrate including the sealing layers; and etching the inter-layer insulation layer to form a contact hole that is aligned with a space between the protrusions of the sealing layers.