A photosensitive resin composition is disclosed.The photosensitive resin composition is characterized by containing (a) a reaction product of a polymer having a specific segment with (3,4-epoxycylohexyl)-methyl methacrylate, (b) a polymerization initiator allowing the initiation of the polymerization of said reaction product when irradiated with an actinic radiation, and (c) a solvent. Preferably, the composition further contains (d) a thermal crosslinker, a compound having a polymerizable unsaturated bond and/or a pigment in addition to the above ingredients.According to the present invention, there is provided the photosensitive resin composition which has such excellent characteristics that it has high sensitivity, it does not require a heat treatment between exposure-development steps, it causes little change of sensitivity and pattern shape with time from the exposure to the development, it has high heat resistance, it permits the use of an aqueous system in the development step and it has good storage stability.