Shutter device for a switchgear apparatus, comprising: - a panel element movable between a protective position, in which said panel element prevents access to stationary electric contacts (109, 190) of said switchgear apparatus, and a non-protective position, in which said panel element enables electric contacts (9, 90) of a circuit-breaker of said switchgear apparatus to couple with said stationary electric contacts (109, 190); - driving lever means (15, 26) for driving said panel element upon a movement of said circuit-breaker from an extracted-non-operative position to an inserted-operative-position with respect to said switchgear apparatus, said driving lever means (15, 26) being movable by driving-pin-elements fixed to said circuit breaker; and - an interlocking assembly (10, 11, 12) configured for locking said driving lever means (15, 26) and blocking said panel element in said protective position so as to prevent manually or unexpectedly moving of said panel element when said circuit-breaker is in said extracted-non-operative position; characterized in that said interlocking assembly (10, 11, 12) comprises: - main-support means fixable to a casing of said switchgear apparatus; - core-plate means to which said driving lever means are fixed, wherein said core-plate means are provided with hinge-pin means through which said driving lever means are pivotally connected to said casing, said hinge-pin means being pivotally coupled with said main-support-means fixable to said casing, and wherein said core-plate means extends radially with respect to and is rotatable around an axis which is perpendicular to said driving lever means and parallel to said panel element; - fail-safe-actuator means pivotally movable between a locking position in which it acts on said core-plate means for locking said driving lever means (15, 26) thus blocking said panel element in said protective position, and a releasing position in which said fail-safe-actuator means disengage from said core-plate-means thus enabling movement of said driving lever means (15, 26), said fail-safe-actuator means being pivotally connected to said main-support-means through pivot means. - a panel element movable between a protective position, in which said panel element prevents access to stationary electric contacts (109, 190) of said switchgear apparatus, and a non-protective position, in which said panel element enables electric contacts (9, 90) of a circuit-breaker of said switchgear apparatus to couple with said stationary electric contacts (109, 190); - driving lever means (15, 26) for driving said panel element upon a movement of said circuit-breaker from an extracted-non-operative position to an inserted-operative-position with respect to said switchgear apparatus, said driving lever means (15, 26) being movable by driving-pin-elements fixed to said circuit breaker; and - an interlocking assembly (10, 11, 12) configured for locking said driving lever means (15, 26) and blocking said panel element in said protective position so as to prevent manually or unexpectedly moving of said panel element when said circuit-breaker is in said extracted-non-operative position; - main-support means fixable to a casing of said switchgear apparatus; - core-plate means to which said driving lever means are fixed, wherein said core-plate means are provided with hinge-pin means through which said driving lever means are pivotally connected to said casing, said hinge-pin means being pivotally coupled with said main-support-means fixable to said casing, and wherein said core-plate means extends radially with respect to and is rotatable around an axis which is perpendicular to said driving lever means and parallel to said panel element; - fail-safe-actuator means pivotally movable between a locking position in which it acts on said core-plate means for locking said driving lever means (15, 26) thus blocking said panel element in said protective position, and a releasing position in which said fail-safe-actuator means disengage from said core-plate-means thus enabling movement of said driving lever means (15, 26), said fail-safe-actuator means being pivotally connected to said main-support-means through pivot means.