A cell culture scaffold containing a gel having a network structure comprised of a synthetic polymer such that cultured cells spread in a shorter time and the number of adsorbed cultured cells per unit area is larger than in the case of using a gel having a network structure comprised of polyacrylic acid, while taking advantage of synthetic polymers with low manufacturing cost, easy quality control and no risk of virus infection in cultured cell. Used as the cell culture scaffold is a gel containing asynthetic polymer obtained by polymerization or copolymerization of a monomer having a sulfonic group such as p-styrenesulfonic acid sodium salt (NaSS) and 2-acrylamide-2-methylpropane sulfonic acid sodium salt (NaAMPS).