To automatically purge a transfer chamber by means of inert gas. There is provided a substrate processing apparatus including a controller that performs control so that a transfer chamber 102 connected to a processing chamber 202 for processing a substrate is purged by gas, the controller having a switching unit that switches a function of exhausting the gas in the transfer chamber 102 in a set direction, and a function of circulating the gas through the transfer chamber 102 in an inert gas atmosphere.