[Problem] To provide a gel which can be produced in a short time, has controlled properties such as modulus and expansion pressure, and has a low polymer concentration. [Solution] A process for producing a polymer gel in which gel-precursor clusters have been crosslinked with one another to form a three-dimensional network structure, characterized by comprising a) a step in which monomer or polymer units that are present in a concentration less than a critical gelation concentration are crosslinked to form the gel-precursor clusters, the gel-precursor clusters having a storage modulus G and a loss modulus G which satisfy the relationship G
