Abstract: A switching device for a transfer switch has a pivotal body, a solenoid, a resilient pushing device and a main spring. The pivotal body has a pivotal axis, a first recess, a second recess and a connecting axis. The first and second recesses are defined adjacent to each other. The connecting axis is defined between the first and second recesses. The solenoid is connected to the pivotal body with a lever and has a driving shaft with a center line. The main spring has a connecting end being connected to the pivotal body at a point on the connecting axis. The lever has a center line. The connecting end of the main spring connected to the connecting axis is offset to the center line of the lever when the center line of the lever aligns with the center line of the driving shaft.