  We report a series of high-resolution N-body simulations designed to examine
the internal physical properties of dark matter halos. A total of fifteen
halos, each represented by $\sim 1$ million particles within the virial radius,
have been simulated covering the mass range of $2\times10^{12}\sim
5\times10^{14} h^{-1}{\rm M_\odot}$. As the first application of these
simulations, we have examined the density profiles of the halos. We found a
clear systematic correlation between the halo mass and the slope of the density
profile at one percent of the virial radius, in addition to the variations of
the slope among halos of the similar mass. More specifically, the slope is
$\sim - 1.5$, -1.3, and -1.1 for galaxy, group, and cluster mass halos,
respectively. Thus we conclude that the dark matter density profiles,
especially in the inner region, are not universal.
