TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: The resin composition further contains an organic compound having number average molecular weight of less than 5000, photoinitiator and inorganic-type microparticles.    TECHNOLOGY FOCUS - POLYMERS - Preparation (Claimed): The polymer is obtained by reacting the prepolymer, polyisocyanate compound and isocyanato alkyl acrylate and/or isocyanato alkyl methacrylate. Alternately, polymer is obtained by reacting the prepolymer, polyisocyanate compound and hydroxyalkyl acrylate and/or hydroxyalkyl methacrylate. Preferred Properties: The prepolymer and polymer have number average molecular weight of 300-50000 and 1000-100000, respectively. Preferred Compound: The polyisocyanate compound is diisocyanate compound, preferably aromatic diisocyanate. The covalent bond is urethane bond. The polymer contains polymerizable unsaturated group, which is double bond. Preferred Polymer: The polymer is of formula: H2C=C(-Rs)-C(=O)-O-Rf-NH-C(=O)-O-Rp-O(-C(=O)-NHRq-NH-C(=O)-O-Rp-O)l-C(=O)-NH-Rr-O-C(=O)-C(-Rt)=CH2 or H2C=C(-Rs)-C(=O)-O-Ru-O-C(=O)-NH-Rq-NH-C(=O)(-O-Rp-O-C(=O)-NH-Rq-NH-C(=O))m-O-Ru-O-C(=O)-C(-Rt)=CH2.Rp=residue obtained by removing both terminal active hydrogen of prepolymer;Rq=residue obtained by removing isocyanate group from diisocyanate compound;Rr=alkyl of isocyanato alkyl acrylate and/or isocyanato alkyl methacrylate;Rs,Rt=methyl or H;l=0 or more;Ru=alkyl portion of hydroxyalkyl acrylate and/or hydroxyalkyl methacrylate;andm=1 or more. EXAMPLE - Poly(oxyethylene oxy propane-dioyl) (in g) (74.8), tolylene diisocyanate (4.63), 2,6-di-t-butyl-4-methyl phenol (0.07), adipic acid (0.01) and di-n-butyl tin dilaurate (0.001) were mixed and stirred at 80 degrees C for 3 hours. Di-n-butyl tin dilaurate (0.001) and 2-methacryloyl oxyethyl isocyanate (3.77) were added and stirred at 80 degrees C for 2 hours. Hydroxy ethyl methacrylate (10.74), trimethylol propane trimethyl acrylate (5.96), 2,2-dimethoxy-2-phenyl acetophenone (0.72), benzophenone (1.21), 2,6-di-t-butyl-4-methyl phenol (0.72), triphenyl phosphate (2.17), Sanol LS-785 (RTM: ) (1.21) and KF-410 (RTM: silicone oil) (1.21) were added, and a photosensitive resin composition was obtained. The composition enabled formation of pattern having high accuracy.