A foot switch having a security mechanism includes a main body, a circuit board, a pedal and a latch. The circuit board is received in the main body. The pedal is provided on the main body. The latch is provided adjacent to the pedal. The pedal is electrically connected to the circuit board via the latch. When the latch and the pedal are pressed, the circuit board is electrically connected to the pedal. The pedal can only generate an unlocking action via the latch, whereby the circuit board is electrically connected to the pedal to output a driving signal. Thus, the foot switch of the present invention can be prevented from being stepped on by mistake, thereby enhancing the safety in use.