It is an object to provide a semiconductor device having a buried multilayer wiring structure in which generation of a resolution defect of a resist pattern is suppressed and generation of a defective wiring caused by the resolution defect is reduced. After a via hole (7) reaching an etching stopper film (4) is formed, annealing is carried out at 300 to 400null C. with the via hole (7) opened. As an annealing method, it is possible to use both a method using a hot plate and a method using a heat treating furnace. In order to suppress an influence on a lower wiring (20) which has been manufactured, heating is carried out for a short time of approximately 5 to 10 minutes by using the hot plate. Consequently, a by-product staying in an interface of an upper protective film (6) and an interlayer dielectric film (5) having a low dielectric constant and a by-product staying in an interface of the etching stopper film (4) and the interlayer dielectric film (5) having a low dielectric constant are discharged so that an amount of the residual by-product can be decreased.