A knob assembly includes a holder including a first surface, a second surface that is opposite to the first surface, and an opening penetrating from the first surface to the second surface, a shaft disposed in the opening, and a knob facing the first surface of the holder and connected to the shaft, wherein the holder includes a hook that is adjacent to an edge of the opening, protrudes from the first surface in a direction of the shaft, and supports the shaft by contacting an outer circumferential surface of the shaft. In addition, various embodiments may be possible.