Abstract: At least one slit having a predetermined shape is formed around a contact region of a lower wiring layer formed on a substrate, and an insulating portion formed integrally with an insulating layer is embedded in this slit. This insulating layer is formed on the lower wiring layer and has a contact hole located at a position corresponding to the contact region. Since the insulating portion as a rectangular projecting portion projects into the slit downwardly from the rigid insulating layer, positional errors caused by thermal expansion of the lower wiring layer in annealing of the upper wiring layer can be suppressed, and an abnormal geometry such as a projection on the upper wiring layer can be prevented. In addition, a semiconductor device free from interwiring short-circuiting and excellent in flatness can be obtained.