A circuit breaker comprises a switching mechanism that including a linkage with a drive joint that is mounted to be rotatable around a rotation axis by a driving force, wherein, during the ON operation, an axis formed by the rotation axis and the point of action of the driving force makes an acute angle with the line of action of the driving force, so that the drive joint causes the tangential force of the driving force to act as input load, at least one hinge part of the linkage is configured in a way that the connecting pin is movably hinged to the long hole-shaped hinge hole, and at least one hinge part of the linkage causes the tangential force to increase by changes in the acute angle as the connecting pin moves from a first side of the long hole-shaped hinge hole to a second side.