Provided is a key switch that enables sufficiently enhancement of the rigidity of a key top. A key switch includes a support plate; a key top disposed on the support plate; a link configured to link the key top with the support plate; a switch; a first arm disposed on a back surface of the key top between the link and a first short-side end of the key top, and extending in a long-side direction of the key top; a second arm disposed on the back surface of the key top between the link and a second short-side end of the key top, and extending in the long-side direction of the key top; and a reinforcement plate mounted on the key top. The reinforcement plate comprises a short-side part extending in the short-side direction of the key top between the first arm and the second arm.