A DC high-speed circuit breaker comprising: an arc chute in which an arc extinguishing space is formed; a fixed main contact arranged on the lower side of said arc chute; and a movable main contact which is arranged on the lower side of said arc chute and is connected/disconnected to/from said fixed main contact, wherein said arc chute includes: first insulation side plates which are arranged so as to sandwich said fixed main contact and said movable main contact from both sides, and form a first arc gas flow passage through which arc gas generated at the fixed main contact and the movable main contact is led to the outside of said arc chute; a plurality of grids which are arranged on the upper side of said fixed main contact and said movable main contact, and form a second arc gas flow passage, said second arc gas flow passage being configured to be a larger width than the space between said first insulation side plates, being communicated to said first arc gas flow passage, and having a larger sectional area than said sectional area of the first arc gas flow passage; and second insulation side plates which are arranged so as to sandwich said grids from both sides, and forms a third arc gas flow passage on the upper side of said grids, said third arc gas flow passage being communicated to said second arc gas flow passage and having a larger sectional area than the sectional area of said second arc gas flow passage. an arc chute in which an arc extinguishing space is formed; a fixed main contact arranged on the lower side of said arc chute; and a movable main contact which is arranged on the lower side of said arc chute and is connected/disconnected to/from said fixed main contact, wherein said arc chute includes: first insulation side plates which are arranged so as to sandwich said fixed main contact and said movable main contact from both sides, and form a first arc gas flow passage through which arc gas generated at the fixed main contact and the movable main contact is led to the outside of said arc chute; a plurality of grids which are arranged on the upper side of said fixed main contact and said movable main contact, and form a second arc gas flow passage, said second arc gas flow passage being configured to be a larger width than the space between said first insulation side plates, being communicated to said first arc gas flow passage, and having a larger sectional area than said sectional area of the first arc gas flow passage; and second insulation side plates which are arranged so as to sandwich said grids from both sides, and forms a third arc gas flow passage on the upper side of said grids, said third arc gas flow passage being communicated to said second arc gas flow passage and having a larger sectional area than the sectional area of said second arc gas flow passage. first insulation side plates which are arranged so as to sandwich said fixed main contact and said movable main contact from both sides, and form a first arc gas flow passage through which arc gas generated at the fixed main contact and the movable main contact is led to the outside of said arc chute; a plurality of grids which are arranged on the upper side of said fixed main contact and said movable main contact, and form a second arc gas flow passage, said second arc gas flow passage being configured to be a larger width than the space between said first insulation side plates, being communicated to said first arc gas flow passage, and having a larger sectional area than said sectional area of the first arc gas flow passage; and second insulation side plates which are arranged so as to sandwich said grids from both sides, and forms a third arc gas flow passage on the upper side of said grids, said third arc gas flow passage being communicated to said second arc gas flow passage and having a larger sectional area than the sectional area of said second arc gas flow passage.