A stacked ferroelectric memory device has selection transistors including a first gate structure, a first impurity region, a second impurity region, a first insulating interlayer covering the selection transistors, bit line structures electrically connected to the first impurity regions, a second insulating interlayer covering the bit line structures, doped single crystalline silicon plugs formed through the first and the second insulating interlayers, each of which contacts the second impurity region and has a height greater than that of the bit line structures, active patterns disposed on the plugs and the second insulating interlayer, each of which contacts the plugs, and ferroelectric transistors disposed on the active patterns, each of which has a second gate structure including a ferroelectric layer pattern and a conductive pattern, a third impurity region and a fourth impurity region. The ferroelectric memory device performs a random access operation and has a high degree of integration.