A cooking appliance including a cooking room; and a rack assembly removably installed in the inside of the cooking room. The rack assembly includes a stationary member fixed in the inside of the cooking room; a moving member configured to slide out of the cooking room; a locking device installed in the stationary member, and configured to lock the stationary member to prevent the stationary member from escaping from the inside of the cooking room; and a noise reducing member configured to reduce noise that is generated when the locking device contacts with at least one of the stationary member and the moving member.