PURPOSE: To improve a water-proofing function by a method wherein a hinge to effect smooth pivotal rise movement and rapid rise and fall pivotal movement is mounted on a door switchgear through a driving gear.

CONSTITUTION: A hinge 18 is formed such that a plate 19 on the fixed side, an auxiliary plate 21, and a plate 22 on the movable side are intercoupled through a lower pivotal shaft 20, an intermediate pivotal shaft 23, and a stop pin 25. The plate 22 on the movable side of the hinge 18 is attached to a waterproof door 1, which is pivotally movable through an opening/closing mechanism. In water-proofing action, when the waterproof door 1 is caused to rise and pivotally move through the plate 22 on the movable side through drive of an opening/closing mechanism of door, the waterproof door 1 is rotated around a lower pivotal shaft 20 with a low rotation radius, and the waterproof door 1 is caused to rapidly rise and seal an inlet and outlet with water.