A semiconductor device includes a semiconductor substrate having a main surface, a first insulating film formed on the main surface, a first coil formed on the first insulating film, a second insulating film formed on the first coil and having a first main surface and first side surfaces continuous with the first main surface, a third insulating film formed on the first main surface of the second insulating film and having a second main surface and second side surfaces continuous with the second main surface, and a second coil formed on the second main surface of the third insulating film. The second insulating film and the third insulating film are formed as a laminated insulating film together. A thickness of the second coil is greater than a thickness of the first coil in a thickness direction of the semiconductor substrate.