According to one embodiment, an isolator includes a first electrode, a second electrode, a conductive body, and a first insulating layer. The second electrode is provided on the first electrode and separated from the first electrode. The conductive body is provided around the first and second electrodes along a first plane perpendicular to a first direction. The first direction is from the first electrode toward the second electrode. The first insulating layer is provided on the second electrode. The first insulating layer includes silicon, carbon, and nitrogen.