NOVELTY - A novel polymer is obtained by polymerizing a prepolymer having active hydrogen group in both terminals, and a polyisocyanate compound, and covalently coupling active hydrogen group of prepolymer with isocyanato alkyl acrylate and/or isocyanato alkyl methacrylate. The prepolymer has solubility parameter of more than 20 J1/2/cm3/2. The polyisocyanate compound has isocyanate group equivalent less than equivalent of active hydrogen group of prepolymer.    USE - Polymer is used for photosensitive resin composition used for laser engraving for manufacturing printing original plate, such as flexo-printing plate, and for manufacturing electroconductive layer, organic light emitting layer used for backlight of display device and illumination device, photoelectric conversion layer for organic thin film solar cell, thin film semiconductor patterned layer, photosensitive layer for electrophotographic photoreceptor, electron-accepting organic layer and/or electron-donating organic layer of photovoltaic device for photosensor, and polysilane thin film of optical switching element (all claimed).    ADVANTAGE - The polymer has excellent solvent resistance and printing durability, and provides photosensitive resin composition capable of forming pattern having excellent accuracy and definition.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) manufacture of polymer;    (2) prepolymer for manufacture of printing plate or printing original plate;    (3) photosensitive resin composition containing the polymer;    (4) manufacture of printing plate or printing original plate, which involves molding the photosensitive resin composition in sheet form or cylindrical form, and carrying out cross-linking curing by irradiating light or electron beam;    (5) manufacture of electroconductive layer, which involves transferring an electroconductive ink to to-be-printed substrate, removing solvent, irradiating with light, and fixing ink to substrate;    (6) manufacture of organic light emitting layer, which involves transferring an organic light emission ink to to-be-printed substrate, removing solvent, irradiating with light, and fixing ink to substrate;    (7) manufacture of photoelectric conversion layer for organic thin film solar cell, which involves transferring ink for photoelectric conversion layer to to-be-printed substrate, removing solvent, irradiating with light, and fixing ink to substrate;    (8) manufacture of thin film semiconductor patterned layer, which involves transferring ink for thin film semiconductor pattern formation to to-be-printed substrate, removing solvent, irradiating with light, and fixing ink to substrate;    (9) manufacture of photosensitive layer for electrophotographic photoreceptor, which involves transferring ink for photosensitive layer formation to to-be-printed substrate, removing solvent, irradiating with light, and fixing ink to substrate;    (10) manufacture of electron-accepting organic layer and/or electron-donating organic layer of photovoltaic device for photosensor, which involves transferring ink for forming electron-accepting and/or electron-donating layer to to-be-printed substrate, irradiating with light, and fixing ink to substrate; and    (11) manufacture of polysilane thin film of optical switching element, which involves transferring ink for forming polysilane thin film layer to to-be-printed substrate, irradiating with light, and fixing ink to substrate.