A semiconductor device includes an interlayer insulating film INS2, adjacent Cu wirings M1W formed in the interlayer insulating film INS2, and an insulating barrier film BR1 which is in contact with a surface of the interlayer insulating film INS2 and surfaces of the Cu wirings M1W and covers the interlayer insulating film INS2 and the Cu wirings M1W. Between the adjacent Cu wirings M1W, the interlayer insulating film INS2 has a damage layer DM1 on its surface, and has an electric field relaxation layer ER1 having a higher nitrogen concentration than a nitrogen concentration of the damage layer DM1 at a position deeper than the damage layer DM1.