A terahertz element of an aspect of the present disclosure includes a semiconductor substrate, first and second conductive layers, and an active element. The first and second conductive layers are on the substrate and mutually insulated. The active element is on the substrate and electrically connected to the first and second conductive layers. The first conductive layer includes a first antenna part extending along a first direction, a first capacitor part offset from the active element in a second direction as viewed in a thickness direction of the substrate, and a first conductive part connected to the first capacitor part. The second direction is perpendicular to the thickness direction and first direction. The second conductive layer includes a second capacitor part, stacked over and insulated from the first capacitor part. The substrate includes a part exposed from the first and second capacitor parts. The first conductive part has a portion spaced apart from the first antenna part in the second direction with the exposed part therebetween as viewed in the thickness direction.