A cross-linking monomer represented by the following Chemical Formula 1, process for preparing a photoresist polymer using the same, and said photoresist polymer: ```wherein, R' and R'' individually represent hydrogen or methyl; m represents a number of 1 to 10; and R is selected from the group consisting of straight or branched C1-10 alkyl, straight or branched C1-10 ester, straight or branched C1-10 ketone, straight or branched C1-10 carboxylic acid, straight or branched C1-10 acetal, straight or branched C1-10 alkyl including at least one hydroxyl group, straight or branched C1-10 ester including at least one hydroxyl group, straight or branched C1-10 ketone including at least one hydroxyl group, straight or branched C1-10 carboxylic acid including at least one hydroxyl group, and straight or branched C1-10 acetal including at least one hydroxyl group.