The invention provides an arc extinguishing chamber for an isolation breaker and the isolation breaker comprising the arc extinguishing chamber. The isolation breaker comprises the arc extinguishing chamber. A main static contact, a main moving contact, a static arc contact and a moving arc contact are correspondingly arranged in the arc extinguishing chamber in the up-down direction. When the isolation breaker is switched off, the main static contact and the static arc contact are located above the corresponding main moving contact and the corresponding moving arc contact, and the static arc contact and the moving arc contact are located on the inner side of the main static contact and the inner side of the main moving contact. A shielding case capable of shielding the static arc contact when the isolation breaker is switched off is arranged between the static arc contact and the main static contact. The shielding case is provided with a lower shielding end, and the lower shielding end is located below the static arc contact when the isolation breaker is switched off. Since the shielding case is arranged in the arc extinguishing chamber, the isolation breaker can be used as both a breaker and an isolation switch; the arc extinguishing chamber is simple in structure, convenient to use and capable of effectively lowering the design cost and the manufacturing cost of the isolation breaker, and has no additional requirements for the operation structure of an existing breaker.