Heat-storage material and refrigerator and cooling container that include the heat-storage material

A heat-storage material that provides a sufficiently large amount of thermal energy as a latent-heat storage material including a semiclathrate hydrate and that improves hysteresis between the solidifying temperature and the melting starting temperature and a refrigerator and a cooling container that include the heat-storage material are provided. The heat-storage material that changes phase at a predetermined temperature includes water, a main agent including a quaternary ammonium salt that forms a semiclathrate hydrate, a pH adjuster that maintains alkaline properties, and a nucleating agent that generates a cation that exhibits positive hydration. In such an aqueous solution maintained to be alkaline, the nucleating agent becomes a nucleus in solidification, and thus, the temperature difference between the solidifying temperature and the melting temperature can be decreased.