An optical keyswitch includes a keycap, a support mechanism, and a switch module. The support mechanism is disposed below the keycap and configured to support the keycap moving upward and downward, the support mechanism comprising a first frame and a second frame, the first frame having a sliding end. The switch module includes a circuit board, an emitter, and a receiver, the emitter and the receiver are electrically connected to the circuit board, and the emitter emitting an optical signal to the receiver. When the keycap is pressed, the first frame is driven by the keycap to slide substantially parallel to the circuit board and block the optical signal with the sliding end, so the switch module is triggered to generate a triggering signal.