A cooking appliance comprising: a cooking room; and a rack assembly removably installed in an inside of the cooking room, the rack assembly comprising: a stationary member fixed in the inside of the cooking room a moving member configured to slide in or out of the cooking room with respect to the stationary member, wherein the moving member is configured to slide between a close position at which the moving member is located in the inside of the cooking room and an open position at which at least one portion of the moving member protrudes 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 holder configured to prevent the stationary member from escaping from the cooking room when the locking device is in a locked state; wherein the locking device comprises a latch configured to be caught by the holder and a lever configured to lift the latch, characterized in that the locking device further comprises a noise reducing member surrounding the lever and configured to reduce noise that is generated when the locking device contacts with at least one of the stationary member and the moving member. a cooking room; and a rack assembly removably installed in an inside of the cooking room, the rack assembly comprising: a stationary member fixed in the inside of the cooking room a moving member configured to slide in or out of the cooking room with respect to the stationary member, wherein the moving member is configured to slide between a close position at which the moving member is located in the inside of the cooking room and an open position at which at least one portion of the moving member protrudes 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 holder configured to prevent the stationary member from escaping from the cooking room when the locking device is in a locked state; wherein the locking device comprises a latch configured to be caught by the holder and a lever configured to lift the latch, characterized in that the locking device further comprises a noise reducing member surrounding the lever and configured to reduce noise that is generated when the locking device contacts with at least one of the stationary member and the moving member. a stationary member fixed in the inside of the cooking room a moving member configured to slide in or out of the cooking room with respect to the stationary member, wherein the moving member is configured to slide between a close position at which the moving member is located in the inside of the cooking room and an open position at which at least one portion of the moving member protrudes 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 holder configured to prevent the stationary member from escaping from the cooking room when the locking device is in a locked state; wherein the locking device comprises a latch configured to be caught by the holder and a lever configured to lift the latch, characterized in that the locking device further comprises a noise reducing member surrounding the lever and configured to reduce noise that is generated when the locking device contacts with at least one of the stationary member and the moving member.