PHOTOSENSITIVE RESIN, PHOTOSENSITIVE COMPOSITION AND PHOTOCROSSLINKED ITEM

The invention provides a photosensitive resin which can readily form, through photo-crosslinking, a surface coating which has hydrophilicity and high bioadaptability; a photosensitive composition containing the photosensitive resin; and a photo-crosslinked structure obtained from the photosensitive composition. The photosensitive resin is represented by the following formula (1): (wherein n represents a mean polymerization degree and is 5 or more; R 1 and R 2 , which may be identical to or different from each other, each represent an alkylene group, an arylene group, an oxyalkylene group, or a single bond; each of X and Y represents a photosensitive unit represented by the following formula (2): or either one of X and Y represents a photosensitive unit represented by the above formula (2) and the other represents an amino group; R 3 represents a group selected from among the groups represented by the following formula set (3): R 4 represents a group selected from among the groups represented by the following formula set (4): at least one of R 3 and R 4 has at least one azido group; and R 5 represents a hydrogen atom, an alkyl group, an acetal-group-containing alkyl group, an aryl group, an aralkyl group, or a substituent containing a base-forming nitrogen atom).