The present invention relates to an alkali development type resin which is obtained by reacting a compound (b) having an alcoholic hydroxyl group and one epoxy group in the molecule with the hydroxyl groups of a phenolic resin (a), and further reacting the hydroxyl groups in the obtained reaction product X with saturated and / or unsaturated polybasic acid anhydride (c); and relates to a photosensitive resin composition containing (A) said alkali development type resin, (B) an epoxy resin, (C) a photopolymerization initiator, and (D) a diluent. Said resin composition has excellent drying properties and alkali developability, and a coated film after curing is outstanding in various characteristics such as adhesion, solder heat resistance, electroless gold plating resistance, PCT resistance, flexibility, thermal shock resistance, and HAST characteristics, and is useful as a solder resist, etching resist, plating resist, or inter-layer insulating material used during manufacture of printed wiring boards.