Abstract: There is provided a positive photosensitive composition which requires no burning, makes it possible to obtain necessary and sufficient adhesion when it is applied under a humidity of 25 to 60%, can be developed at a low alkali intensity, makes it possible to carry out development with keeping high sensitivity while forming no residue, ensures sharp edges, can provide a very hard resist film and is improved in scratch resistance in the handling before development. The composition comprises (A) an alkali-soluble high molecular substance having in the molecule thereof at least one carboxyl group, (B) a photo-thermal conversion material which absorbs infrared rays from an image exposure light source to convert the rays to heat, and (C) a thiol compound.