Abstract: A key, which is pressed for constituting close circuit, includes a key cap, a movable arm and a bottom plate. A bottom of the key cap is joined to a bend part of the movable arm. A pivot part of the movable arm is movably joined to a pivot hole of the bottom plate. The bend part surrounds at least two adjacent lateral sides of the bottom of the key cap to constitute a support plane. When the key cap is pressed down at any one spot on the key cap, the pressing force is supported by the bend part and moves the key cap downward directly instead of inclining to the side of the pressed spot. The key provides simple structure for easy assembly and requires less precision for saving fabrication cost.