A detection apparatus includes conversion elements and switch elements disposed below the conversion elements; insulating layers are disposed between the conversion elements and switch elements. Each conversion element includes a first electrode corresponding to a switch element. A second electrode extends over the plurality of conversion elements; and a semiconductor layer formed between the first electrodes and the second electrode extends over the plurality of conversion elements. Insulating layers include first regions located immediately below the first electrodes and a second region located between the first regions. A third electrode is disposed in the second region and between the insulating layers. The third electrode is supplied with a potential that sets a potential of a part where the second region is in contact with the semiconductor layer to a value between a potential of the second electrode and a potential of the first electrode.