The present invention provides a positive type photosensitive resin composition having good heat resistance, namely, a photosensitive resin composition which comprises an alkali-soluble resin component (A) and a photosensitizer (B), characterized in that the component (A) contains a resin component (A1) comprising structural units (a1) represented by the general formula (a1): (a1) wherein R0 is hydrogen or methyl; R1 is a single bond or alkylene having 1 to 5 carbon atoms; R2 is alkyl having 1 to 5 carbon atoms; a is an integer of 1 to 5 and b is an integer of 0 to 4, with the proviso that the sum of a and b is 5 or below; and when two or more R2's are present, the R2's can be the same or different from each other.