An input/output driving circuit may include a pad, an open-drain driving circuit, a high-voltage protection unit and a control unit. The open-drain driving circuit may be configured to output a transmission signal to the pad. The high-voltage protection unit may be configured to input a received signal from the pad. The control unit may include a gate control logic, a transmission control logic and an inverter for controlling the open-drain driving circuit. The control unit may also include a reception control logic and a well voltage generation unit for controlling the high-voltage protection unit.