A gelatinizer is provided having a component which promises to have biological compatibility, which can easily be mass-produced by a simple method, and which can solidify a large amount of water or aqueous solution when only a very small weight of it is used.This invention is a hydrogelatinizer represented by the general formula: R-A.sub.n where A, which may be identical or different, are respectively nucleotides, n is 2 or 3, and R is a hydrocarbon chain (when n is 2, R is bivalent, and when n is 3, R is trivalent), said hydrocarbon being bonded to a phosphoric acid part of said nucleotides.