A transfer system includes: a transfer chamber having a side wall provided thereon with a plurality of processing chambers in which a processing is performed on a substrate under a decompressed atmosphere, and configured such that the substrate is transferred in the decompressed atmosphere; a plurality of robots fixed in the transfer chamber and configured to transfer the substrate; and a movable buffer configured to hold the substrate and move in a horizontal direction along the side wall between the side wall and the robots in the transfer chamber. The robots exchange the substrate between the movable buffer and the processing chambers in cooperation with a movement of the movable buffer.