Particles can be suppressed from adhering to a substrate. A substrate processing apparatus includes a carry-in/out chamber, a transfer chamber, and a delivery chamber. In the carry-in/out chamber, the substrate is carried in and out with respect to a carrier, and in the transfer chamber, a transfer path for the substrate toward a substrate processing chamber, where a predetermined process is performed on the substrate, is formed. Further, the delivery chamber is arranged between the carry-in/out chamber and the transfer chamber. Moreover, an internal pressure of the delivery chamber is higher than an internal pressure of the carry-in/out chamber and an internal pressure of the transfer chamber.