A method for manufacturing a nickel-metal hydride battery includes: a first step of preparing a first nickel-metal hydride battery having a positive electrode including nickel hydroxide (Ni(OH)2); and a second step of manufacturing the second nickel-metal hydride battery by performing 600% overcharging to the prepared first nickel-metal hydride battery. The 600% overcharging is a process for supplying the first nickel-metal hydride battery with an amount of electric power of 600% of the rated capacity of the first nickel-metal hydride battery.