A substrate processing apparatus includes one or more substrate processing units 11 to 18 each processing a substrate 3 with a processing fluid; processing fluid supply units 19 and 20 supplying the heated processing fluid to the substrate processing units 11 to 18; and a controller 21 controlling the processing fluid supply units 19 and 20. The processing fluid supply units 19 and 20 include a storage tank 35 storing the processing fluid; a heating heat exchanger 51 heating the processing fluid; and a supply path 52 supplying the processing fluid to the substrate processing units 11 to 18. The supply path 52 includes a bypass path 71 bypassing the heating heat exchanger 51 at an upstream of the substrate processing units 11 to 18. The processing fluid heated by the heating heat exchanger 51 and the processing fluid supplied from the bypass path 71 are mixed to be supplied.