Disclosed herein are an apparatus and method for aligning a bill supplied to a transfer path with a center line of the transfer path. The apparatus includes a fixed support unit which moves a bill in a transfer direction of the transfer path, a movable support unit which is disposed in succession to the fixed support unit and is provided so as to be movable in a lateral direction of the transfer path, a bill position sensor which senses the position of the bill that moves on the fixed support unit and the movable support unit, and a controller which is controls a lateral displacement of the movable support unit in response to information about the position of the bill, thus aligning the bill with the center line.