an external operating handle mechanism for a mold cased circuit breaker comprising : an external operating handle ; a pinion gear coupled to the external operating handle to be rotatable in response to a rotation of the external operating handle ; a movable member provided with a rack gear portion coupled to the pinion gear to be linearly movable according to the rotation of the pinion gear , and provided with a handle connecting portion connected to the handle of the mold cased circuit breaker to linearly move the handle of the mold cased circuit breaker ; and a guide member for guiding the movable member to linearly move , by which it is easy to control a stroke required for a displacement of the handle of the mold cased circuit breaker and the displacement of the external operating handle according to the stroke , and it is possible to accurately and efficiently transfer power upon performing a reset operation . accordingly , unreasonable force may not be applied to resin molding components related to the reset operation including a handle among switching mechanisms , and thus damage or deformation of these components and a unsuccessful or imperfect reset operation can be prevented .