Curdlan is a polysaccharide that is expected to work as a gene carrier. We synthesized chemically cross-linked Curdlan (CCC) gel and examined its characterization. CCC gels were swollen with alkaline water over pH ∼10.2, but shrunk with acid and neutral water. Swelling ratios of the present CCC gels with water were found to be 45 times at the most and dependent on the fraction of cross-linker reagent. These volume phase transition gels that are sensitive to pH are useful and ecological as a biocompatible and biodegradable material.