  Based on quantum hadrodynamics with a finite cutoff, the effective masses of
vector mesons(\omega, \rho) in nuclear medium are calculated. We use a
low-energy effective Lagrangian which is obtained by integrating high-energy
quantum fluctuations. Although we use an artificial cutoff, the
cutoff-dependence can be removed order by order. It is shown that there is a
strong correlation between the effective \omega -meson mass and the effective
nucleon mass at the normal density. It is also found that the effective
\rho-meson mass m_\rho^* decreases as density increases. The rate of the
decrease becomes smaller at high density. As a result, at the normal density,
the m^*_\rho/m_\rho is 0.85 \sim 0.95.
