A key switch includes a base, a key cap, a first support member and a second support member. The key cap is disposed with respect to the base. The first support member and the second support member are disposed between the key cap and the base. The first support member has a first linkage structure. The second support member has a second linkage structure. The first linkage structure and the second linkage structure abut against each other, such that the first support member and the second support member rotate synchronously with respect to a horizontal axis. When one of the first support member and the second support member horizontally moves with respect to the other one of the first support member and the second support member within a predetermined range along the horizontal axis, the first linkage structure and the second linkage structure keep abutting against each other.