In a key switch, in which, between the holder (20) overlapped and fixed on the switch substrate (10) and the keycap (50), interposing the pantograph assembly (30) disposed in X-figured two movable members (31), 32 and the mounting plate (40) by pushing the rubber spring (11) of the switch substrate (10) with the keycap (50) for shrinking the rubber spring to close the movable contact, the holder (20) is formed with a supporting plate (22) made from a thin stainless steel and a U-figured resin made supporting frame (23) on the supporting frame (23) the clamping portion (26) to support one end hinge pin (35) of the one movable member (31) and the sliding stepped portion (27) to support one end sliding hinge pin (36) of the other movable member (32) are formed and the supporting frame (23) is clamped between the raised pieces (24) provided on the periphery of the opening (21) of the supporting plate (22) and the switch substrate (10).