The seismic velocities for three kinds of enstatite (low clinoenstatite, L-CEn; orthoenstatite, OEn; and high-pressure clinoenstatite, HP-CEn), which is a major component in the upper mantle, were estimated using molecular dynamics simulations based on the interatomic potential model. The calculated seismic velocities, Vp and Vs, for OEn are slower than those of L-OEn up to 6 GPa and 1000 K. The velocities in HP-CEn are faster than those in OEn at the transition pressure between OEn and HP-CEn. Furthermore, anisotropy of the seismic velocity, in particular Vp parallel to <100> > <001> > <010>, is observed. We conclude that the transitions in enstatites are related to the seismic discontinuity observed at depths less than 410 km and that enstatite is as an important a mineral as olivine for the mineralogical model and for the anisotropic propagation of seismic waves in the Earth's upper mantle.