The present disclosure relates to an arc extinguishing assembly, including side members which are spaced apart by a certain distance and disposed to face each other; an exhaust which is installed at an upper part of the side member; a plurality of grids which are installed between the side members and having both ends fixed to each of the side members; and an arc guide whose one side is coupled to the side member and which is installed at a lower part of the plurality of grids, wherein the arc guide is made of a material having heat resistance, and a circuit breaker including the same.