Memory device and memory unit

There are provided a memory device and a memory unit that make it possible to improve retention property of a resistance value in low-current writing. The memory device of the technology includes a first electrode, a memory layer, and a second electrode in order, in which the memory layer includes an ion source layer containing one or more transition metal elements selected from group 4, group 5, and group 6 in periodic table, one or more chalcogen elements selected from tellurium (Te), sulfur (S), and selenium (Se), and one or both of boron (B) and carbon (C), and a resistance change layer having resistance that is varied by voltage application to the first electrode and the second electrode.