A nickel metal hydride storage battery included a battery case, and a group of electrode plates arranged in the battery case, wherein the battery case includes a battery case main body having a hole and a lid for closing the hole. The battery case includes a first portion made of a metal or a laminate of a metal and a resin, and a second portion made of a resin; and an area of the first portion is 20% or more and 90% or less with respect to the entire battery case. Thus, a nickel metal hydride storage battery is capable of controlling the amount of hydrogen permeating the battery case and capable of suppressing the long-term deterioration.