An operating handle locking device for use with an electrical switchgear such as a circuit interrupter comprises a locking plate for blocking the movement of the operating handle between the ON position and the OFF position, and a support plate secured to the circuit interrupter for supporting the lock plate, the locking plate being locked in the operating handle locking position relative to the support plate by a locking member. The switchgear may have a trip button for tripping the switchgear from the exterior, and the locking plate may have a cover portion for covering the trip button when the locking plate is in an operating handle locking position. A cover portion may also be provided in the locking plate for covering the reset button of the circuit interrupter when in the operating handle locking position.