  We calculate stellar oscillations including the hadron-quark mixed phase
considering the finite size effects. We find that it is possible to distinguish
whether the density discontinuity exists or not in the stars, even if one will
observe the gravitational waves of the fundamental mode. Additionally, the
normalized eigenfrequencies of pressure modes depend strongly on the stellar
mass and on the adopted equation of state. Especially, in spite of the fact
that the radius of the neutron star with $1.4M_\odot$, which is standard mass,
is almost independent from the equation of state with quark matter, the
frequencies of pressure modes depend on the adopted equation of state. Thus,
via observing the many kinds of gravitational waves, it will be possible to
make a restriction on the equation of state.
