An isolator includes a first electrode; a first insulating portion on the first electrode; a second electrode on the first insulating portion; a second insulating portion around the second electrode; and a first dielectric portion on the second electrode and the second insulating portion. The second insulating portion is provided along a first plane perpendicular to a first direction from the first electrode toward the second electrode. The second electrode including a bottom surface facing the first insulating portion, an upper surface facing the first dielectric portion, a first side surface connected to the bottom surface, and a second side surface connected to the upper surface and the first side surface. The upper surface is wider than the bottom surface in a second direction along the first plane. The first side surface is tilted with respect to the bottom surface and the second side surface.