The present invention is related to a photosensitive resin composition containing: a vinyl-based copolymer (I) obtained by polymerizing a monomer mixture containing a monomer (a) having a phenolic hydroxyl group and a carboxyl group-containing vinyl monomer (b); a quinonediazide compound (II) and a compound (III) represented by the following formula (5), and to a photosensitive dry film and a method for forming a patter by using the photosensitive resin composition.According to the present invention, it is possible to provide a photosensitive resin composition which can form a resist film in which the occurrence of crack is suppressed, the film reduction of the unexposed area is suppressed, and sensitivity and resolution are excellent, and to provide a photosensitive dry film and a method for forming a pattern by using the photosensitive resist composition [In the formula, Y is a straight or branched hydrocarbon group of 1 to 6 carbon atoms; 1 and m are respectively independently an integer of 1 to 3; n is 1 or 2; p and q are respectively independently 0 or 1.]