A semiconductor device includes a semiconductor substrate, an insulating film formed above the semiconductor substrate, and a plurality of first buried wirings and a plurality of second buried wirings located in the insulating film at predetermined intervals alternately in a direction parallel to a surface of the semiconductor substrate. Each second buried wiring is formed so that a width between both side surfaces thereof is increased from a lower end toward an upper portion and at an upper surface the width is larger than a width at an upper surface of each first buried wiring.