An object of the present invention is to provide a wafer transfer robot mount/demount cart for simply mounting and demounting a wafer transfer robot which is linearly, substantially horizontally reciprocated in a wafer transfer apparatus to transfer wafers. A pair of mount/demount cart-side rails 9 which can be connected to a pair of wafer transfer apparatus-side guide rails mounted inside a wafer transfer apparatus D is mounted on a raised portion 5 of the mount/demount cart A. A joint rail S is mounted in a gap between the pair of wafer transfer apparatus-side rails and the pair of mount/demount cart-side rails 9 so as to slide a wafer transfer robot R onto the pair of mount/demount cart-side rails 9 via the joint rail S.