Disclosed is a method for forming a polysilicon plug of a semiconductor device. The method comprises the steps of: forming a stacked pattern of a wordline and a hard mask film on a semiconductor substrate comprising a cell region and a peripheral circuit region; forming a spacer on a sidewall of the stacked pattern; forming an interlayer insulating film on the semiconductor substrate; polishing the interlayer insulating film via a CMP process using the hard mask film as a polishing barrier film; forming a barrier film on the semiconductor substrate including the interlayer insulating film; selectively etching the barrier film and the interlayer insulating film to form a landing plug contact hole; depositing a polysilicon film filling the landing plug contact hole on the semiconductor substrate; blanket-etching the polysilicon film using the barrier film as an etching barrier film; and polishing the polysilicon film and the barrier film using the hard mask film as a polishing barrier film to form a polysilicon plug.