A memory cell of a magnetic memory device has an MTJ element and one end of the memory cell is selectively electrically connected to a ground potential line. A first bit line is electrically connected to the other end of the memory cell. A sense amplifier amplifies a difference in potential between the first bit line and a second bit line complementary to the first bit line so that the difference is equal to or larger than a difference between an internal power potential and a ground potential. A connection circuit disconnects the MTJ element from an electric connection between the ground potential line and the sense amplifier.