Composition for forming hydrogel, hydrogel, and method for producing composition for forming hydrogel

A hydrogel-forming composition comprising a vinyl alcohol polymer having an ethylenically unsaturated group and having a polymerization degree of 1500 or more,

• in which the ethylenically unsaturated group introduction ratio is 0.01 to 10 mol % in all the structural units constituting the vinyl alcohol polymer, and
• in which no microorganisms detectable by the sterility test method (direct method) specified in the general test methods of the Japanese Pharmacopoeia are present,
• wherein the ethylenically unsaturated group is at least one kind selected from the group consisting of a vinyl group, a (meth)acryloyloxy group, a (meth)acryloylamino group, a vinylphenyl group, a norbornenyl group, and derivatives thereof, and
• wherein a tensile strength at break of a crosslinked hydrogel of the hydrogel-forming composition is 0.040 to 0.320 MPa.