Provided is a semiconductor device in which influence resulting from a cell function change can be reduced. The semiconductor device includes a function cell designed using a basic cell including a first wiring layer provided over a main surface of a semiconductor substrate and having a predetermined pattern and a second wiring layer provided over the first wiring layer and having a predetermined pattern. The function cell corresponds to the basic cell which is modified to have a predetermined function by changing the pattern of the second wiring layer at a design stage. The function cell has a first layout and a second layout which are disposed in juxtaposition in one direction in a plane parallel with the main surface. The function cell is provided with the predetermined function by coupling together wires belonging to the respective second wiring layers of the first layout and the second layout.