A circuit breaker in which arc shielding members are provided for predetermined contacts among a plurality of contact pairs arrayed in parallel, so that the arc will take place between predetermined contacts when the contacts are opened. The arc shielding members are made of a material having resistivity greater than that of the conductors to which the contacts are attached. The arc shielding members work to effectively inject metallic particles of contact material into the arc, so that the arcing voltage is rapidly raised and so that feet of the arc will not spread to the conductors in the vicinities of the contacts.
