An object is to reduce variations in programming behavior from memory element to memory element. Furthermore, an object is to obtain a semiconductor device with excellent writing characteristics and in which the memory element is mounted. The memory element includes a first conductive layer, a metal oxide layer, a semiconductor layer, an organic compound layer, and a second conductive layer, where the metal oxide layer, the semiconductor layer, and the organic compound layer are interposed between the first conductive layer and the second conductive layer; the metal oxide layer is provided in contact with the first conductive layer; and the semiconductor layer is provided in contact with the metal oxide layer. By use of this kind of structure, variations in programming behavior from memory element to memory element are reduced.