To provide a production method by which an organic-inorganic composite hydrogel forming a three-dimensional net structure out of a clay mineral and a macromolecular polymer in a wide range of the content of the clay mineral, and exhibiting excellent mechanical properties can be produced without using an initiator.

The method for producing the organic-inorganic composite hydrogel includes dispersing or dissolving a water-swellable clay mineral (b) subjected to a surface treatment with plasma, and a water-soluble (meth)acrylic monomer (a) in an aqueous medium (c), and polymerizing the (meth)acrylic monomer (a) without using the polymerization initiator by heating and/or irradiation with ultraviolet rays.