Current interruption device and electricity storage device using the same

A current interruption device configured to interrupt a conduction between an electrode terminal and an electrode in a case where pressure in a casing of a electricity storage device exceeds a predetermined value, the current interruption device comprising

• a first conducting member fixed to the casing;
• a second conducting member disposed at a position opposed to the first conducting member;
• a first deforming member disposed between the first conducting member and the second conducting member, the first deforming member configured to make contact with the second conducting member when the pressure in the casing is equal to or less than the predetermined value, and configured not to make contact with the second conducting member when the pressure in the casing exceeds the predetermined value;
• and
• a second deforming member disposed on an opposite side of the first deforming member relative to the second conducting member, the second deforming member comprising a projection which projects toward a center portion of the second conducting member, wherein a center portion of the second deforming member projects in a direction away from the second conducting member when the pressure in the casing is equal to or less than the predetermined value, and the center portion of the second deforming member moves toward the second conducting member so that the projection makes contact with the second conducting member when the pressure in the casing exceeds the predetermined value,
• wherein a restricting structure that restricts a movement of the second deforming member is a groove disposed on the second conducting member on an opposite side from a first deforming member side,
• the end portion of the second deforming member is in the groove, and
• an outer peripheral edge of the second deforming member makes contact with a side surface of the groove.