A semiconductor device includes a scan input circuit, a master latch, a slave latch, a first inverter, and a scan output circuit. The scan input circuit is configured to receive a scan input signal, a first data signal, and a scan enable signal and select any one of the first data signal and the scan input signal in response to the scan enable signal to output a first select signal. The master latch is configured to latch the first select signal and output a first output signal. The slave latch is configured to latch the first output signal and output a second output signal. The first inverter is configured to invert the second output signal. The scan output circuit is configured to receive a signal output from the slave latch and an external signal and output a first scan output signal.