According to one embodiment, a sensor includes a first control line, a first signal line, a first detection switch, a common electrode, a first detection electrode, a first circuit and a second circuit. The common electrode is located above the first control line, the first signal line and the first detection switch, opposed to the first control line, the first signal line and the first detection switch. The first detection electrode is located above the common electrode. The first circuit and the second circuit are located under the common electrode, and are opposed to the common electrode.