A key stabilizer is provided, in which the key stabilizer includes a keycap and a balance bar. The keycap has a bottom surface and two protruding portions disposed thereon. The keycap moves back and forth along a vertical direction between a top position and a bottom position. Each of the two protruding portions has an engaging portion at the end thereof. The bottom surface faces the bottom position, and the two protruding portions are arranged along a horizontal direction that is perpendicular to the vertical direction. The balance bar has a hinge portion and two side portions respectively connected to both ends of the hinge portion. The hinge portion is positioned on a rotation axis parallel to the horizontal direction. The end of each of the two side portions that is away from the hinge portion is inserted into the engaging portion.