To provide an organic-inorganic composite hydrogel not only having excellent mechanical properties but also having high swellability with physiological salt solution and high swellability with water, to provide a dried body thereof, and to provide a method for producing them.

The organic-inorganic composite hydrogel having both of the high swellability with the physiological salt solution and the high swellability with the water, and formed of a water-soluble polymer of acrylic monomers and a water-swellable clay mineral is obtained by using a monomer represented by formula (1) (wherein, R1 is hydrogen or methyl; R2 is 2-3C alkylene; n is an integer of 2-99; and Y is methoxy or hydroxy) in combination with an amino group-containing (meth)acrylate as the water-soluble acrylic monomers. The dried body thereof has excellent flexibility.