Provided is a three-dimensionally stacked field-effect transistor (3DSFET) device which includes: a 1st lower source/drain region and a 2nd lower source/drain region connected to each other through a 1st lower channel structure controlled by a 1st gate structure; and a 1st upper source/drain region and a 2nd upper source/drain regions, respectively above the 1st lower source/drain region and the 2nd lower source/drain region, and connected to each other through a 1st upper channel structure controlled by the 1st gate structure, wherein the 2nd lower source/drain region and the 2nd upper source/drain region form a PN junction therebetween.