  This paper presents a microscopic calculation of the flux-flow resistivity
$\rho_{f}$ for s-wave type-II superconductors with arbitrary impurity
concentrations near the upper critical field $H_{c2}$. It is found that, as the
mean free path $l$ becomes longer, $\rho_{f}$ increases gradually from the
dirty-limit result of Thompson [Phys. Rev. B{\bf 1}, 327 (1970)] and Takayama
and Ebisawa [Prog. Theor. Phys. {\bf 44}, 1450 (1970)]. The limiting behaviors
suggest that $\rho_{f}(H)$ at low temperatures may change from convex downward
to upward as $l$ increases, thus deviating substantially from the linear
dependence $\rho_{f}\propto H/H_{c2}$ predicted by the Bardeen-Stephen theory
[Phys. Rev. {\bf 140}, A1197 (1965)].
