In a conventional semiconductor device, an excessive etching occurs in a section where an opening for contact plug is formed, causing a damage to a diffusion layer located under the opening.A semiconductor device 1 includes a region D1 for forming an electric circuit, and a seal ring 30 (guard ring) that surrounds the region D1 for forming the electric circuit. A DRAM 40 is formed in the region D1 for forming the electric circuit. Interlayer insulating films 22, 24, 26 and 28 are formed on a semiconductor substrate 10. The seal ring 30 is formed in the interlayer insulating films 22, 24, 26 and 28, and at least a portion there of is located spaced apart from the semiconductor substrate 10.