A semiconductor device including an electrostatic discharge (ESD) protection circuit includes an input port, a logic circuit receiving an input signal applied to the input port and generating an output signal based on the input signal, and an ESD protection circuit adjusting a level of the input signal when the level of the input signal exceeds a predetermined range. The ESD protection circuit includes a first fin and a second fin arranged on a semiconductor substrate in parallel, and a gate electrode formed in a direction crossing the first fin and the second fin, each of the first fin and the second fin includes a source region, a drain region, and a channel region disposed between the source region and the drain region, the channel region is disposed under the gate electrode, a source region of the first fin and a drain region of the second fin are disposed at a first side of the gate electrode, and a drain region of the first fin and a source region of the second fin are disposed at a second side of the gate electrode.