A semiconductor device includes a first n-type source/drain region 48a and a second p-type source/drain region 48b formed on a semiconductor substrate 20 away from side surfaces of first and second gate electrodes 39a, 39b at a first interval W4 respectively, a second n-type source/drain region 48c and a first p-type source/drain region 48d formed on the semiconductor substrate 20 away from side surfaces of third and fourth gate electrodes 39c, 39d at a second interval W3, which is wider than the first interval W4, respectively, and third and fourth insulating sidewalls 43c, 43d extended onto source/drain extensions 42c, 42d on both sides of third and fourth gate electrodes 39c, 39d from edges of upper surfaces of the third and fourth gate electrodes 39c, 39d respectively.