The charged black hole is considered from the viewpoint of D0-brane in the
Matrix theory. It can be obtained from the Kaluza-Klein mechanism by boosting
the Schwarzschild black hole in a circle, which is the compactified one
dimensional space. Especially, how the extremal limit is realized by the
Boltzmann gas of D0-brane, has been shown. In the course of our discussion, the
Virial theorem for the statistical average plays an important role.Comment: LaTeX file, no figure, 8 page