An ultraviolet sensor includes a substrate; a diamond layer, placed on the substrate, functioning as a detector; and at least one pair of surface electrodes arranged on the diamond layer. The diamond layer has a detecting region present at the surface thereof, the detecting region has at least one sub-region exposed from the surface electrodes, and the sub-region has a covering layer, made of oxide or fluoride, lying thereon. A method for manufacturing the ultraviolet sensor includes a step of forming a diamond layer, functioning as a detector, on a substrate; a step of forming at least one pair of surface electrodes on the diamond layer; and a step of forming a covering layer, made of oxide or fluoride, on at least one sub-region of a detecting region present at the surface of the diamond layer, the sub-region being exposed from the surface electrodes.