. . . . "An adhesive composition comprising (a) an acidic group-containing polymerizable monomer; (b) a polymerizable monomer represented by the general formula (I): wherein R1 is hydrogen atom or methyl group; R2 is a halogen atom, hydroxyl group, mercapto group or ???O???R3???OH group, wherein R3 is an alkylene group having 6 to 25 carbon atoms; and Y is oxygen atom or sulfur atom; and (c) a hydrophilic" .