ARC extinguishing mechanism for mold cased circuit breaker

An arc extinguishing mechanism for the mold cased circuit breaker comprises a plurality of arc grids stacked on one another in a perpendicular direction and supporting plates for supporting the arc grids, and each of the arc grids comprises a U-shaped plate portion made of a ferromagnetic material, and having two leg portions, a plurality of supporting protrusions laterally extending from the U-shaped plate portion to be flush with the U-shaped plate portion, thus to allow the U-shaped plate portion to be coupled to the supporting plates for support, and bent portions extending from the leg portions, respectively, by being bent in a perpendicular direction, to minimize an air gap between the adjacent arc grids stacked on each other so as to increase a force of inducing arc generated in the arc chamber toward the arc grids.