An interlock apparatus configured to block an operation of a third circuit breaker while a first circuit breaker and a second circuit breaker operate, the interlock apparatus comprising: a base adapted to be attached to the third circuit breaker, a driver, a guide, a blocker and a channel part, wherein the driver is adapted to be coupled to a rotating shaft of the first circuit breaker and the second circuit breaker, and the driver comprises a first intermediator, a first rotator and a first elastic part, wherein the first intermediator has an accommodation part and the first rotator is engaged with the first intermediator; wherein the base has the guide being rectilinearly movable at the base through the channel part to provide a movement path to the blocker; wherein the blocker comprises a mover, a second rotator and a second intermediator, wherein the second rotator includes a first engagement part and a second engagement part, wherein the first engagement part is engaged with the second intermediator, wherein the second engagement part is engaged with one of a central part of the mover and a protrusion of the guide, wherein the mover comprises a first connector adapted to be connected to the first circuit breaker, a second connector _adapted to be connected to the second circuit breaker and the central part disposed between the first connector and the second connector; wherein the driver is adapted to be coupled to a rotatable shaft of the third circuit breaker through the first rotator and the first intermediator via an accommodating part; wherein the channel part passes through the base and is configured to provide the rectilinear movement path of the mover depending on operations of the first circuit breaker and the second circuit breaker; and wherein the second intermediator comprises a stopper; wherein the stopper is configured, when the second intermediator blocks the operation of the third circuit breaker in response to the operation of the first circuit breaker and the second circuit breaker, to rotate along the second rotator to come into contact with the accommodation part of the first intermediator; and, when the second intermediator allows the operation of the third circuit breaker in response to the operation of at least one of the first circuit breaker and the second circuit breaker, to rotate along the second rotator to be separated from the accommodation part of the first intermediator. a base adapted to be attached to the third circuit breaker, a driver, a guide, a blocker and a channel part, wherein the driver is adapted to be coupled to a rotating shaft of the first circuit breaker and the second circuit breaker, and the driver comprises a first intermediator, a first rotator and a first elastic part, wherein the first intermediator has an accommodation part and the first rotator is engaged with the first intermediator; wherein the base has the guide being rectilinearly movable at the base through the channel part to provide a movement path to the blocker; wherein the blocker comprises a mover, a second rotator and a second intermediator, wherein the second rotator includes a first engagement part and a second engagement part, wherein the first engagement part is engaged with the second intermediator, wherein the second engagement part is engaged with one of a central part of the mover and a protrusion of the guide, wherein the mover comprises a first connector adapted to be connected to the first circuit breaker, a second connector _adapted to be connected to the second circuit breaker and the central part disposed between the first connector and the second connector; wherein the second rotator includes a first engagement part and a second engagement part, wherein the first engagement part is engaged with the second intermediator, wherein the second engagement part is engaged with one of a central part of the mover and a protrusion of the guide, wherein the mover comprises a first connector adapted to be connected to the first circuit breaker, a second connector _adapted to be connected to the second circuit breaker and the central part disposed between the first connector and the second connector; wherein the driver is adapted to be coupled to a rotatable shaft of the third circuit breaker through the first rotator and the first intermediator via an accommodating part; wherein the channel part passes through the base and is configured to provide the rectilinear movement path of the mover depending on operations of the first circuit breaker and the second circuit breaker; and wherein the second intermediator comprises a stopper; wherein the stopper is configured, when the second intermediator blocks the operation of the third circuit breaker in response to the operation of the first circuit breaker and the second circuit breaker, to rotate along the second rotator to come into contact with the accommodation part of the first intermediator; and, when the second intermediator allows the operation of the third circuit breaker in response to the operation of at least one of the first circuit breaker and the second circuit breaker, to rotate along the second rotator to be separated from the accommodation part of the first intermediator.