Arc chamber of circuit breaker

An arc chamber of a circuit breaker, comprising:

• a plurality of grids arranged outside of a motion trajectory of a movable contact at a predetermined interval and including a body portion and a leg portion extending from one side of the body portion;
• and
• a fixing cap having an accommodating portion press-fitted into the leg portion,
• wherein the fixing cap is provided with a coupling portion extending to a side surface of the body portion from one side thereof,
• wherein a plurality of second protrusions disposed adjacent to the leg portion is provided at both side surfaces of the body portion,
• wherein a plurality of fixing holes fitted to the second protrusions is provided on the coupling portion, and
• wherein each of the second protrusions is provided with an interference prevention groove provided at both ends thereof in contact with the body portion.