The present invention relates to a polymer prepared by synthesizing monomer having a derivative of cholic acid, deoxycholic acid or lithocholic acid bonded to norbornene, and then homopolymerizing these monomer, copolymerizing these monomer with maleic anhydride, or copolymerizing these monomer, maleic anhydride and 2-hydroxyethyl 5-norbornene-2-carboxylate and/or 5-norbornene-2carboxylic acid, and its use as a photoresist. The polymer synthesized according to the present invention is dissolved in a solvent, together with a photo-acid generator, and filtered through a filter to make a photoresist solution which can be used to produce a lithographic image on a silicon wafer.