There is provided a substrate processing method using a processing chamber that is provided with a first process gas supply region, a first exhaust port through which a first process gas supplied to the first process gas supply region is exhausted, a second process gas supply region, a second exhaust port through which a second process gas supplied to the second process gas supply region is exhausted, and a communication space through which the first exhaust port and the second exhaust port communicate with each other, wherein an exhaust pressure in the first exhaust port is set higher than an exhaust pressure in the second exhaust port by a predetermined pressure so as to perform a substrate process while preventing infiltration of the second process gas into the first exhaust port.