A water absorbent material, comprising, as a main component, a water absorbent resin which has a structure in which a anhydropolyamino acid having an ethylenically unsaturated double bond is grafted with polysaccharides, wherein at least a portion of the anhydropolyamino acid is hydrolyzed and crosslinked, has high water absorbency and high biodegradability even if the anhydropolyamino acid has a low molecular weight.