A memory device of a resistance variation type, in which data retaining characteristic at the time of writing is improved, is provided. The memory device includes: a plurality of memory elements in which a memory layer is provided between a first electrode and a second electrode so that data is written or erased in accordance with a variation in electrical characteristics of the memory layer; and pulse applying means applying a voltage pulse or a current pulse selectively to the plurality of memory elements. The memory layer includes an ion source layer including an ionic-conduction material and at least one kind of metallic element, and the ion source layer further contains oxygen.