To provide a method for forming an ultrahigh heat-resistant positive pattern by using a positive photosensitive composition in the process which requires high heat resistance of a photoresist pattern such as manufacturing of a TFT active matrix substrate.

After a photosensitive composition containing (a) an alkali-soluble resin, (b) a photosensitive agent having a quinone diazide group, (c) a photoacid generating agent, (d) a crosslinking agent, and (e) a solvent is applied on a substrate, exposed through a mask, and developed to remove the exposed part to form a positive image, the obtained positive image is entirely exposed and if necessary, post-baked. When a 1, 2-naphthoquinone diazide-4-sulfonyl compound is used as the photosensitive agent having a quinone diazide group, this compound also functions as an acid generating agent and thereby, the component (c) can be omitted.