A selection device for selecting an output state of a switch device is disclosed. The selection device includes a power source, a rectification element, a driving unit, and a control unit. The switch device includes an upper-arm switch and a lower-arm switch. The power source provides a power signal. The rectification element is coupled to the power source. The driving unit includes a totem circuit coupled to the upper-arm switch and a storage element coupled to the rectification element. The control unit transmits the power signal to the driving unit by the rectification element according to a control signal. The upper-arm switch is driven by the totem circuit to select the output state when the power signal is received by the driving unit.