A semiconductor device includes a plurality of pads configured to receive a plurality of external signals, an internal circuit configured to perform a predetermined internal operation in response to one of the external signals that is inputted through one of the plurality of pads, and a signal transferring unit configured to receive the external signal, output the external signal to an internal circuit an output signal during a normal mode, and output a fixed signal regardless of changes in the external signal to the internal circuit in a test mode.