PROBLEM TO BE SOLVED: To provide a hydrogel excellent in bleed-out resistance.SOLUTION: The hydrogel includes a polymer matrix, water, and a polyhydric alcohol having an oxyalkylene group. The polymer matrix comprises a copolymer of (meth)acrylamide, another monofunctional monomer having one polymerizable carbon-carbon double bond in the molecule, and a crosslinkable monomer. The another monofunctional monomer is at least one selected from the group consisting of diacetone (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-(meth)acryloylmorpholine, and N-(2-hydroxyethyl)(meth)acrylamide.
