A locking device for an operating mechanism of a gas insulated switchgear, the locking device comprising: a driving shaft lever connected to a driving shaft of the operating mechanism to perform a rotation motion; first and second link rods (20, 25) coupled to upper and lower ends of the driving shaft lever, respectively, to transfer the motion; a driven shaft lever coupled to a driven shaft, having upper and lower ends connected to the first and second link rods (20, 25), respectively; and wherein the driven shaft is configured to be rotated by a force transferred by the driven shaft lever, characterized in that the locking device further comprises: a stopping groove (31, 32, 33) formed on the outer surface of the driven shaft lever; a supporter installed at a tank of the gas insulated switchgear; a locking lever rotatably coupled to the supporter, the locking lever locking the motion of the driven shaft lever when being inserted into the stopping groove (31, 32, 33); and, a lever pin inserted through the locking lever and serving as a rotation shaft of the locking lever, wherein when the locking lever is rotated in a counterclockwise direction based on the lever pin, the locking lever is separated from the one stopping groove (31, 32, 33) and when the locking lever is rotated in a clockwise direction based on the lever pin, the locking lever is inserted into one of the stopping groove (31, 32, 33). a driving shaft lever connected to a driving shaft of the operating mechanism to perform a rotation motion; first and second link rods (20, 25) coupled to upper and lower ends of the driving shaft lever, respectively, to transfer the motion; a driven shaft lever coupled to a driven shaft, having upper and lower ends connected to the first and second link rods (20, 25), respectively; and wherein the driven shaft is configured to be rotated by a force transferred by the driven shaft lever, characterized in that the locking device further comprises: a stopping groove (31, 32, 33) formed on the outer surface of the driven shaft lever; a supporter installed at a tank of the gas insulated switchgear; a locking lever rotatably coupled to the supporter, the locking lever locking the motion of the driven shaft lever when being inserted into the stopping groove (31, 32, 33); and, a lever pin inserted through the locking lever and serving as a rotation shaft of the locking lever, wherein when the locking lever is rotated in a counterclockwise direction based on the lever pin, the locking lever is separated from the one stopping groove (31, 32, 33) and when the locking lever is rotated in a clockwise direction based on the lever pin, the locking lever is inserted into one of the stopping groove (31, 32, 33). a stopping groove (31, 32, 33) formed on the outer surface of the driven shaft lever; a supporter installed at a tank of the gas insulated switchgear; a locking lever rotatably coupled to the supporter, the locking lever locking the motion of the driven shaft lever when being inserted into the stopping groove (31, 32, 33); and, a lever pin inserted through the locking lever and serving as a rotation shaft of the locking lever, wherein when the locking lever is rotated in a counterclockwise direction based on the lever pin, the locking lever is separated from the one stopping groove (31, 32, 33) and when the locking lever is rotated in a clockwise direction based on the lever pin, the locking lever is inserted into one of the stopping groove (31, 32, 33).