To provide a gel sheet having strength by subjecting an aqueous solution containing polyoxyethylene oxide having a weight average molecular weight of a prescribed value in a specific range and polyvinyl alcohol(PVA) having an average molecular weight of a prescribed value in a specific range at a weight ratio of a specific range to irradiation with ionizable radiation.

This gel sheet for medical material is obtained by subjecting an aqueous solution containing an polyoxyethylene oxide having the weight average molecular weight of 1×105 to 4×106 and a PVA having the average molecular weight of 1,200 to 2,000 at the weight ratio of 95:5 to 60:40 to the irradiation with the ionizable radiation. The gel sheet is prepared by first dissolving the polyoxyethylene oxide and the PVA in water so as to attain the weight ratio described above, then irradiating the resultant polyoxyethylene oxide/PVA- containing aqueous solution with high energy to crosslink the aqueous solution. The ionizable radiation is preferably γ rays from cobalt 60 and the electron beams by an accelerator for the purpose of industrial production.