Nickel-metal hydride storage battery

An object of the present invention is to provide a nickel-metal hydride storage battery having a long life in an electrolyte solution containing a large amount of NaOH. The nickel-metal hydride storage battery includes a negative electrode containing a hydride storage alloy having a CaCu 5 -type crystal structure and containing at least a Ni element and a rare earth element. The rare earth element is partly substituted with an Y element. The nickel-metal hydride storage battery contains an electrolyte solution containing NaOH in an amount of 2.0 M or more.