The purpose of the present invention is to provide a hydrogel that has excellent mechanical strength and that does not present problems in terms of toxicity to living organisms, and a method for producing the same. This hydrogel is produced by allowing a polyvinyl alcohol-based resin (A) having a syndiotacticity of 32% or more, expressed as triads, to swell in water (B), dissolve under thermocompression conditions, and then cool.
