A door structure of an electric rail car is provided to block outside noise and vibration. The door structure of the electric rail car includes a door frame, a guide rail and a sealing device. The door frame has an opening thereinside. The guide rail guides an opening and a closing of the door frame. The sealing device is inserted into the opening, descends to make contact with the guide rail when the door frame is closed, and ascends to be spaced apart from the guide rail when the door frame is open.