A scan flip-flop circuit includes an input unit and an output unit. The data output unit is configured to provide a data output terminal with a data output signal in response to a data input signal and a first control signal in a first operation mode, and the data output unit is configured to prohibit the data output terminal from being provided with a power supply voltage and a ground voltage applied to the scan flip-flop circuit in response to the data input signal and the first control signal in a second operation mode. The scan output unit is configured to provide a scan output terminal with a scan output signal in response to a scan input signal and a second control signal in the second operation mode.