A rupture disk for a gas insulated switchgear which includes a thin dome plate that includes a first flange portion and a first dome-shaped portion formed in a dome shape, at the center of the first flange portion; and a rupture guide plate which includes a second flange portion, laminated on the first flange portion, and a second dome-shaped portion has a plurality of slots formed therein to define a rupture shape so that a part of the first dome-shaped portion is ruptured, in a predetermined shape, when an internal pressure increases. End portions of slots, disposed at both edges among the plurality of slots, are provided with rupture restriction openings, respectively, to configure a hinge portion of the second dome-shaped portion.