The stability of hydrogen clathrate hydrate was investigated using a classical Molecular Dynamic (MD) calculation code “MXDTRICL” as a theoretical approach. Arranging hydrogen molecules one by one into host-frame of the hydrogen hydrates, the inclusion energy of their system was evaluated, where Lennard-Jones potential and two types of TIP4P potentials were adopted on the MD calculations as intermolecular potentials. From the result, it is concluded that multiple molecules are included in both large and small cages so that the storage density could attain higher than 6wt% for any potential. Observation of the movement of H2 molecules in the cage under various conditions revealed that H2 molecules are not stable in the cage and a few part of the H2 molecules come in and go out of the cage through the center hole between hexagons.