The present invention provides a method of processing a substrate, comprising a reflow process for forming a desired pattern by dissolving a resist pattern, whereby occurrence of defectives, such as disconnection, can be prevented, and a pattern having an appropriate uniformity can be formed efficiently on each predetermined area desired to be masked. From a photoresist pattern 206 including thicker film portions and thinner film portions, the thinner film portions are removed by a re-developing process. Next, the photoresist so formed by the re-developing process on a backing layer 205 is dissolved such that it passes through a stepped portion 205a formed at each edge portion 205b of the backing layer 205, thereby masking a predetermined area Tg. Upon masking the predetermined area Tg, the photoresist 206 is dissolved in a first dissolving-speed mode on the backing layer 205, and then after the photoresist to be dissolved reaches the stepped portion 205a, the photoresist 206 is dissolved in a second dissolving-speed mode which is slower than the first dissolving-speed mode.