A substrate processing apparatus and method for effectively removing an organic material such as a photoresist without using sulfuric acid are provided. The substrate processing apparatus includes a support module, in which a substrate is inverted and seated, and an ultraviolet light source is installed, wherein the substrate is arranged so that one surface of the substrate faces the support module, and the ultraviolet light source irradiates ultraviolet rays to one surface of the substrate; a nozzle installed in the support module; and a fluid supply module for supplying a fluid to one surface of the substrate through the nozzle.