Disclosed are a substrate processing apparatus and a substrate processing method, wherein a resist can be removed from a substrate well and a processing liquid used for the resist removal can be reused. Specifically disclosed is a substrate processing apparatus comprising a substrate holding means for holding a substrate, a persulfuric acid-producing means for producing a persulfuric acid by using a sulfuric acid, a mixing means for mixing the persulfuric acid produced by the persulfuric acid-producing means with a sulfuric acid having a higher temperature and a higher concentration than the sulfuric acid used in the persulfuric acid-producing means, and an ejecting means for ejecting the mixed solution of the persulfuric acid and the sulfuric acid, which is obtained by the mixing means as a processing liquid for removing a resist from the substrate, onto the substrate held by the substrate holding means.