An optical keyswitch includes a keycap, a supporting mechanism having a protrusion disposed under the keycap to support the keycap to move downward or upward, and a switch module including a circuit board, an emitter, and a receiver. The emitter and the receiver are electrically connected to the circuit board. The emitter emits an optical signal to the receiver. When the keycap is not pressed, the receiver receives the optical signal of a first intensity. When the keycap is pressed, the protrusion moves along with the keycap, and the protrusion changes the optical signal received by the receiver to have a second intensity different from the first intensity, so the switch module is triggered to generate a triggering signal.