A circuit breaker including a moving contact assembly (A') that is brought into contact with or separated from fixed contact points, the moving contact assembly (A') comprising: a shaft that is rotatable in a first direction or a second direction opposite to the first direction by means of a switching mechanism; a moving contact that is held to be rotatable in the first or second direction with respect to the shaft, with the rotation axis of the moving contact not fitted on the shaft; and springs that apply torque to the moving contact in the first direction, the shaft comprising: stopping faces that are formed in the direction opposite to the first direction in which the moving contact rotates; and guiding faces that are curved from the stopping faces and face the rotation axis of the shaft, the moving contact comprising: first surfaces that are formed on the radius of rotation of the moving contact and brought into contact with the stopping face; and sliding surfaces that are slanted from the first surfaces and toward the center of rotation with respect to the line of action of a tangential force (F') of torque at the points of contact with the guiding faces, wherein the position of the moving contact is corrected depending on positional errors of the points of contact when the moving contact comes into contact with the fixed contact points, and when the moving contact is separated from the fixed contact points, the component force (F'×cosθ') of the torque directed toward the sliding surfaces causes the sliding surfaces to move with respect to the guiding faces against the frictional force and returns the moving contact to the normal position where the rotation axis of the moving contact coincides with the rotation axis of the shaft. a shaft that is rotatable in a first direction or a second direction opposite to the first direction by means of a switching mechanism; a moving contact that is held to be rotatable in the first or second direction with respect to the shaft, with the rotation axis of the moving contact not fitted on the shaft; and springs that apply torque to the moving contact in the first direction, the shaft comprising: stopping faces that are formed in the direction opposite to the first direction in which the moving contact rotates; and guiding faces that are curved from the stopping faces and face the rotation axis of the shaft, stopping faces that are formed in the direction opposite to the first direction in which the moving contact rotates; and guiding faces that are curved from the stopping faces and face the rotation axis of the shaft, the moving contact comprising: first surfaces that are formed on the radius of rotation of the moving contact and brought into contact with the stopping face; and sliding surfaces that are slanted from the first surfaces and toward the center of rotation with respect to the line of action of a tangential force (F') of torque at the points of contact with the guiding faces, first surfaces that are formed on the radius of rotation of the moving contact and brought into contact with the stopping face; and sliding surfaces that are slanted from the first surfaces and toward the center of rotation with respect to the line of action of a tangential force (F') of torque at the points of contact with the guiding faces, wherein the position of the moving contact is corrected depending on positional errors of the points of contact when the moving contact comes into contact with the fixed contact points, and when the moving contact is separated from the fixed contact points, the component force (F'×cosθ') of the torque directed toward the sliding surfaces causes the sliding surfaces to move with respect to the guiding faces against the frictional force and returns the moving contact to the normal position where the rotation axis of the moving contact coincides with the rotation axis of the shaft.