A vacuum apparatus includes process chambers, and a transfer chamber coupled to the process chambers. The transfer chamber includes one or more vacuum ports, thorough which a gas inside the transfer chamber is exhausted, and vent ports, from which a vent gas is supplied. The one or more vacuum ports and the vent ports are arranged such that air flows from at least one of the vent ports to the one or more vacuum ports are line-symmetric with respect to a center line of the transfer chamber.